What is class and object in Java ?

<div dir="ltr" style="text-align: left;" trbidi="on"> <h2 style="text-align: left;"> <b><span style="font-family: Georgia, Times New Roman, serif; font-size: small; line-height: 115%;"><span style="color: #0b5394;">What is class and object?</span><o:p></o:p></span></b></h2> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjM7LRFt46JAk-xJizFxui1htbhKoQDx_aky9ACaYGZk1howlFo4t_wnHwAhzbp7t_0RSrHBSBwmdTiLdWxQFKCKmgGWccEfCI0e9MVwF29Tm1PJwh7UDj13e0iyWkzvgiBivVS9zd3jLc/s1600/java_object_class_difference.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: Georgia, Times New Roman, serif;"><img alt="What is class and object in Java" border="0" height="218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjM7LRFt46JAk-xJizFxui1htbhKoQDx_aky9ACaYGZk1howlFo4t_wnHwAhzbp7t_0RSrHBSBwmdTiLdWxQFKCKmgGWccEfCI0e9MVwF29Tm1PJwh7UDj13e0iyWkzvgiBivVS9zd3jLc/s400/java_object_class_difference.png" title="What is class and object in Java" width="400" /></span></a></div> <div class="separator" style="clear: both; text-align: center;"> <span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l1 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l1 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, Times New Roman, serif;"><span style="text-align: left; text-indent: -0.25in;"><ol style="text-align: left;"> <li><span style="text-indent: -0.25in;">  </span><span style="text-indent: -0.25in;">A class is a <b>template from which objects are created</b>. That is objects are instance of a class.</span></li> <li><span style="text-indent: -0.25in;"> </span><span style="text-indent: -0.25in;">When you create a class, you are creating a new data-type. You can use this type to declare objects of that type.</span></li> <li><span style="text-indent: -0.25in;"> </span><span style="text-indent: -0.25in;">Class defines structure and behavior (data & code) that will be shared by a set of objects</span></li> </ol> </span><span style="text-align: left; text-indent: -0.25in;">A class is declared by use of the </span><b style="text-align: left; text-indent: -0.25in;">class keyword</b><span style="text-align: left; text-indent: -0.25in;">. Classes may contain data and code both.</span><br /><span style="text-align: left; text-indent: -0.25in;">The general form of al class definition:</span></span><ul style="text-align: left;"> </ul> </div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">            class ClassName<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">            {<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        type instance variable1;<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        type instance variable2;<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        <o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        type methodname1 (parameter list)<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        {<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                                    body of method;<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        }<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        type methodname2 (parameter list)<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        {<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                                    body of method;<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">                        }<o:p></o:p></span></div> <div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> <span style="color: #1d1d1e; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial;">             }<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Georgia, Times New Roman, serif;">v  <!--[endif]-->The data or variable are called <b>instance variable</b>. The code is contained within methods.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Georgia, Times New Roman, serif;">v  <!--[endif]-->The method and variables defined within a class are called <b>member of the class</b>.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div> <h3 style="text-align: left;"> <span style="color: #0b5394; font-family: Georgia, Times New Roman, serif; font-size: small;">Example of Class</span></h3> <div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div> <pre class="java" name="code"><span style="font-family: Georgia, Times New Roman, serif;">class Box { double width; double height; double depth; } class BoxDemo { public static void main (String args[]) { Box mybox = new Box (); double vol; mybox.width =10; mybox.height = 20; mybox.depth = 30; vol = mybox.width * mybox.height * mybox.depth; System.out.println (“Volume is: - “+vol); } } </span></pre> <pre class="java" name="code"></pre> <pre class="java" name="code"><div class="MsoNormal" style="mso-layout-grid-align: none; text-align: justify; text-autospace: none;"> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l4 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span> <li><span style="font-family: Georgia, Times New Roman, serif;">Each object contains its own copy of each variable defined by the class. </span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l4 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span> <li><span style="font-family: Georgia, Times New Roman, serif;"> So, every Box object contains its own copy of the instance variables width, height and depth. </span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l4 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span> <li><span style="font-family: Georgia, Times New Roman, serif;">To access these variables, you will use the <b>dot (.) operator</b>. The dot operator links the name of the object with the name of an instance variable. </span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <h4> <span style="font-family: Georgia, Times New Roman, serif;"> <b><span style="color: #0b5394;">Declaring Object</span></b><span style="color: #0b5394;"> </span><o:p></o:p></span></h4> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Georgia, Times New Roman, serif;">•        Box mybox;     // declare ref. to object which contains null value.<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Georgia, Times New Roman, serif;">•        mybox = new Box ();   // allocate a Box object.<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> <span style="color: #0b5394;"> </span></span><div class="MsoNormal" style="text-align: justify;"> <h4> <span style="font-family: Georgia, Times New Roman, serif;"> <span style="color: #0b5394;"><b>General form of a new</b> <o:p></o:p></span></span></h4> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">            class var = new classname ();<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">            mybox = new Box ();<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">Where:<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">            class var =  variable of the class type.<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">            classname = name of the class.<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l2 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <div style="text-align: left;"> <span style="font-family: Georgia, 'Times New Roman', serif;"> </span></div> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"><div style="text-align: left;"> <span style="text-indent: -0.25in;"> </span><span style="text-indent: -0.25in;">The classname followed by parentheses specifies the constructor for the class.</span></div> </span><span style="font-family: Georgia, Times New Roman, serif;"><div style="text-align: left;"> </div> <div style="text-align: left;"> </div> </span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l2 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"><div style="text-align: left;"> <span style="text-indent: -0.25in;">A constructor defines what occurs when an object of a class is created.</span></div> </span><div style="text-align: left;"> </div> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"><div style="text-align: left;"> <span style="text-indent: -0.25in;"> </span><span style="text-indent: -0.25in;">Most classes explicitly define their own constructors within their class definition but if no explicit constructor is specified then java will automatically supply a default constructor.</span></div> </span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l2 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <div style="text-align: left;"> <span style="font-family: Georgia, 'Times New Roman', serif;"> </span></div> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"><div style="text-align: left;"> <span style="text-indent: -0.25in;"> </span><span style="text-indent: -0.25in;">This is the case with Box. This is default constructor. </span></div> </span><ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <h4> <span style="font-family: Georgia, Times New Roman, serif;"> <b><span style="color: #0b5394;">Assigning Object Reference Variable</span></b><span style="color: #0b5394;"> </span></span></h4> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">Box b1 = new Box ();</span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">Box b2 = new b1;<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l1 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"> After this executes, b1 and b2 will both refer to the same object. </span><br /> <ul style="text-align: left;"> </ul> </div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l1 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;">The assignment of b1 to b2 did not allocate any memory or copy any part of the original object.</span> <ul style="text-align: left;"> </ul> </div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l1 level1 lfo2; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;"> </span><span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;">It simply makes b2 refer to the same object as does b1. Thus, any changes made to the object through b2 will affect the object to which b1 is referring,since they are the same object. </span> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><h3 style="text-align: left;"> <span style="font-family: Georgia, Times New Roman, serif; font-size: small;"> <b><span style="color: #0b5394;">Introducing Methods</span></b><span style="color: #0b5394;"> </span></span></h3> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">type name (parameter-list)<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">{<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">            body of method<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">} <o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"> </span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;">Where:</span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><b>Type : </b>Specifies the type of data returned by the method.If the method does not return a value its ret urn type must be void. <o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><b>Name: </b>Specifies the name of the method. <o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><b>Parameter-list: </b>It is a sequence of type & identifiers pairs separated by commas.<o:p></o:p></span></div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="margin-left: .5in; mso-list: l5 level1 lfo3; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> <span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;">Parameters are variables that receive the value of the argument passed to the method when it is called. If the method has no parameters, then the parameter list will be empty.</span> <ul style="text-align: left;"> </ul> </div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l5 level1 lfo3; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <span style="font-family: Georgia, Times New Roman, serif; text-align: left; text-indent: -0.25in;"> Methods that have a return type other than void return a value to the calling routine </span><span style="font-family: Georgia, 'Times New Roman', serif; text-align: left; text-indent: -0.25in;">using the following form of the return statement;</span> <ul style="text-align: left;"><span style="font-family: Georgia, Times New Roman, serif;"> </span></ul> </div> <span style="font-family: Georgia, Times New Roman, serif;"> </span><div class="MsoNormal" style="text-align: justify;"> <span style="font-family: Georgia, Times New Roman, serif;"><b>Return value;</b> </span></div> <h3 style="text-align: left;"> </h3> <h3 style="text-align: left;"> <span style="font-family: Georgia, Times New Roman, serif; font-size: small;"><b><span style="color: #0b5394;">Types of Methods</span></b><span style="color: #0b5394;"> </span> </span></h3> <span style="font-family: Georgia, Times New Roman, serif;"> </span><ol start="1" style="margin-top: 0in;" type="1"><span style="font-family: Georgia, Times New Roman, serif;"> </span> <li class="MsoNormal" style="mso-list: l3 level1 lfo4; tab-stops: list .5in; text-align: justify;"><span style="color: #444444; font-family: Georgia, Times New Roman, serif; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Does not return value – void</span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span> <li class="MsoNormal" style="mso-list: l3 level1 lfo4; tab-stops: list .5in; text-align: justify;"><span style="color: #444444; font-family: Georgia, Times New Roman, serif;">Returning a value <o:p></o:p></span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span> <li class="MsoNormal" style="mso-list: l3 level1 lfo4; tab-stops: list .5in; text-align: justify;"><span style="color: #444444; font-family: Georgia, Times New Roman, serif;">Method which takes parameter <o:p></o:p></span></li> <span style="font-family: Georgia, Times New Roman, serif;"> </span></ol> <span style="font-family: Georgia, Times New Roman, serif;"> </span></pre> <br /></div>

What is class and object in Java ?

What is class and object?    A class is a template from which objects are created . That is objects are instance of a class.   W...

Read more »

Garbage Collection in Java

<div dir="ltr" style="text-align: left;" trbidi="on"> <h2 style="text-align: left;"> <b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Garbage Collection</span></span></b></h2> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRJpC9-555vMPHjR6C6zrmrAbcKHQgp_z5mkWHPG78aVXwidpvIA6xpTHvrFv2kySTzO0XEznSH243i1Y5RYTJwDo8ABodSa8IB0WfmD81ssHxdpIZQbwDuzUQ_zVKhpdafznU0uqxgfg/s1600/java1-001.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRJpC9-555vMPHjR6C6zrmrAbcKHQgp_z5mkWHPG78aVXwidpvIA6xpTHvrFv2kySTzO0XEznSH243i1Y5RYTJwDo8ABodSa8IB0WfmD81ssHxdpIZQbwDuzUQ_zVKhpdafznU0uqxgfg/s400/java1-001.jpg" width="400" /></a></div> <div> <b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;"><br /></span></span></b></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <br /> <ul style="text-align: left;"> <li><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"><span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Objects are dynamically allocated by using the <b>new</b> operator.</span></li> <li><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"><span style="font-family: 'Times New Roman'; font-size: 7pt;"> </span></span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">In some languages, such as C++, dynamically allocated objects must be manually released by use of a <b>delete</b> operator.</span></li> <li><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-style: italic; mso-fareast-font-family: Wingdings;"><span style="font-family: 'Times New Roman'; font-size: 7pt;"> </span></span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Java handles deallocation for you automatically. The technique that accomplishes this is called <b><i>garbage collection</i></b><i>.</i></span></li> <li>When no references to an object exist, that object is assumed to be no longer needed, and the memory occupied by the object can be reclaimed.</li> </ul> </div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> </div> <div class="MsoListParagraph" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial; line-height: 12pt; margin-bottom: 0.0001pt;"> <span style="background-color: white;">Garbage collection (GC) is a form of automatic <span style="text-decoration: none;">memory management</span>. The garbage collector, or just collector, attempts to reclaim <a href="http://en.wikipedia.org/wiki/Garbage_(computer_science)"><span style="text-decoration: none;">garbage</span></a>, or memory occupied by <span style="text-decoration: none;">objects</span> that are no longer in use by the <span style="text-decoration: none;">program</span>. Garbage collection was invented by <span style="text-decoration: none;">John McCarthy</span> around 1959 to solve problems in <span style="text-decoration: none;">Lisp</span>.<span style="color: #1f0707; font-size: 10.5pt;"><o:p></o:p></span></span></div> <div class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial; line-height: 12pt; margin-bottom: 0.0001pt;"> <span style="background-color: white; color: #1f0707; font-size: 10.5pt;"><br /></span></div> <div class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial; line-height: 12pt; margin-bottom: 0.0001pt;"> <img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDIMS5YVMl3H59J0YqzyRKMkEHTiA2hjs0u1Td5F2EM1mBcLeQrpjwqtVqoSms_A2B49Uu3ulmJSNXFTRIVtCSXO6kcJWsBEFsA0xDNi3DQhOYpzLxbA8NYb3vNu3NSSfA76sVmLnHhGtt/s640/java_memory.png" /></div> <div class="MsoNormal" style="margin-bottom: 0.0001pt;"> <br /></div> <div class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial; line-height: 12pt; margin-bottom: 0.0001pt;"> <span style="background-color: white;"><span style="color: #d78787; text-decoration: none;"><!--[if gte vml 1]><v:shapetype id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"> <v:stroke joinstyle="miter"/> <v:formulas> <v:f eqn="if lineDrawn pixelLineWidth 0"/> <v:f eqn="sum @0 1 0"/> <v:f eqn="sum 0 0 @1"/> <v:f eqn="prod @2 1 2"/> <v:f eqn="prod @3 21600 pixelWidth"/> <v:f eqn="prod @3 21600 pixelHeight"/> <v:f eqn="sum @0 0 1"/> <v:f eqn="prod @6 1 2"/> <v:f eqn="prod @7 21600 pixelWidth"/> <v:f eqn="sum @8 21600 0"/> <v:f eqn="prod @7 21600 pixelHeight"/> <v:f eqn="sum @10 21600 0"/> </v:formulas> <v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/> <o:lock v:ext="edit" aspectratio="t"/> </v:shapetype><v:shape id="Picture_x0020_1" o:spid="_x0000_i1025" type="#_x0000_t75" alt="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDIMS5YVMl3H59J0YqzyRKMkEHTiA2hjs0u1Td5F2EM1mBcLeQrpjwqtVqoSms_A2B49Uu3ulmJSNXFTRIVtCSXO6kcJWsBEFsA0xDNi3DQhOYpzLxbA8NYb3vNu3NSSfA76sVmLnHhGtt/s640/java_memory.png" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDIMS5YVMl3H59J0YqzyRKMkEHTiA2hjs0u1Td5F2EM1mBcLeQrpjwqtVqoSms_A2B49Uu3ulmJSNXFTRIVtCSXO6kcJWsBEFsA0xDNi3DQhOYpzLxbA8NYb3vNu3NSSfA76sVmLnHhGtt/s1600/java_memory.png" style='width:480pt;height:224.25pt;visibility:visible;mso-wrap-style:square' o:button="t"> <v:imagedata src="file:///C:\Users\DIVYES~1\AppData\Local\Temp\msohtmlclip1\01\clip_image001.png" o:title="java_memory"/> </v:shape><![endif]--><!--[if !vml]--><!--[endif]--></span><span style="color: #1f0707;">Garbage collection is often portrayed as the opposite of</span><span style="color: #3d85c6;"> <a href="http://en.wikipedia.org/wiki/Manual_memory_management"><span style="text-decoration: none;">manual memory management</span></a></span><span style="color: #1f0707;">, which requires the programmer to specify which objects to deallocate and return to the memory system. However, many systems use a combination of approaches, including other techniques such as </span>stack allocation<span style="color: #1f0707;"> and </span><span style="text-decoration: none;">region inference</span><span style="color: #1f0707;">.<o:p></o:p></span></span></div> <div class="MsoNormal" style="margin-bottom: 0.0001pt;"> <br /></div> <div class="MsoNormal" style="background-position: initial initial; background-repeat: initial initial; line-height: 12pt; margin-bottom: 0.0001pt;"> <span style="background-color: white;">Resources other than memory, such as <span style="text-decoration: none;">network sockets</span>, database <span style="text-decoration: none;">handles</span>, user interactionwindows, and file and device descriptors, are not typically handled by garbage collection. Methods used to manage such resources, particularly <span style="text-decoration: none;">destructors</span>, may suffice to manage memory as well, leaving no need for GC. Some GC systems allow such other resources to be associated with a region of memory that, when collected, causes the other resource to be reclaimed; this is called <span style="text-decoration: none;">finalization</span>. Finalization may introduce complications limiting its usability, such as intolerable latency between disuse and reclaim of especially limited resources, or a lack of control over which thread performs the work of reclaiming.<span style="color: #1f0707;"><o:p></o:p></span></span></div> <div class="MsoNormal" style="margin-left: .5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> </div> <div class="MsoNormal"> <br /></div> </div>

Garbage Collection in Java

Garbage Collection    Objects are dynamically allocated by using the new operator.   In some languages, such as C++, dynamically...

Read more »

What is JVM ?

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px;"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJjtZ4Kf8_IuqoxMfKmBuIj18G81LqJwg5iX3NZk0OSvzBadoklBjwjaCB4wUBjpttFI5msMv3qsva3bsYVcMh_c8NJ1PMMgJEBmE_N6wQLMmqlSTXZF35Pjl3C6i4ZCg-gEYiiL2COmM/s1600/jvm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJjtZ4Kf8_IuqoxMfKmBuIj18G81LqJwg5iX3NZk0OSvzBadoklBjwjaCB4wUBjpttFI5msMv3qsva3bsYVcMh_c8NJ1PMMgJEBmE_N6wQLMmqlSTXZF35Pjl3C6i4ZCg-gEYiiL2COmM/s320/jvm.jpg" width="320" /></a></div> <br /> Each of the preceding buzzwords is explained in <a href="http://java.sun.com/docs/white/langenv/" style="color: #2970a6; margin: 0px; padding: 0px; text-decoration: none;" target="_blank"><em style="margin: 0px; padding: 0px;">The Java Language Environment</em></a> , a white paper written by James Gosling and Henry McGilton.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px;"> In the Java programming language, all source code is first written in plain text files ending with the <code style="margin: 0px; padding: 0px;">.java</code> extension. Those source files are then compiled into <code style="margin: 0px; padding: 0px;">.class</code> files by the <code style="margin: 0px; padding: 0px;">javac</code>compiler. A <code style="margin: 0px; padding: 0px;">.class</code> file does not contain code that is native to your processor; it instead contains <em style="margin: 0px; padding: 0px;">bytecodes</em> — the machine language of the Java Virtual Machine<sup style="margin: 0px; padding: 0px;"><a href="http://tecnoesis.wordpress.com/wp-admin/#FOOT" style="color: #2970a6; margin: 0px; padding: 0px; text-decoration: none;">1</a></sup> (Java VM). The <code style="margin: 0px; padding: 0px;">java</code>launcher tool then runs your application with an instance of the Java Virtual Machine. An overview of the software development process.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: center;"> <img alt="Java Process" height="83" src="http://tecnoesis.files.wordpress.com/2009/08/java-process.jpeg?w=482&h=83" style="border: 0px; margin: 0px; max-width: 600px; padding: 0px;" title="Java Process" width="482" /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: center;"> <br /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px;"> One characteristic of Java is portability, which means that computer programs written in the Java language must run similarly on any supported hardware/operating-system platform. This is achieved by compiling the Java language code, not to machine code but to Java bytecode – instructions similar to machine code but intended to be interpreted by a virtual machine (VM) written specifically for the host hardware. End-users commonly use a Java Runtime Environment (JRE) installed on their own machine for standalone Java applications, or in a Web browser for Java applets. Standardized libraries provide a generic way to access features such as graphics, threading, networking and much more. A major benefit of using bytecode is porting. However, the overhead of interpretation means that interpreted programs almost always run more slowly than programs compiled to native executables would, and Java suffered a reputation for poor performance. This gap has been narrowed by a number of optimization techniques introduced in the more recent JVM implementations.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px;"> Because the Java VM is available on many different operating systems, the same <code style="margin: 0px; padding: 0px;">.class</code> files are capable of running on Microsoft Windows, the Solaris <sup style="margin: 0px; padding: 0px;">TM</sup> Operating System (Solaris OS), Linux, or Mac OS. Some virtual machines, such as the <a href="http://java.sun.com/products/hotspot/" style="color: #2970a6; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">Java HotSpot virtual machine</a>, perform additional steps at runtime to give your application a performance boost. This include various tasks such as finding performance bottlenecks and recompiling (to native code) frequently used sections of code. Through the Java VM, the same application is capable of running on multiple platforms.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: center;"> <img alt="Java Cross Platform Support" height="332" src="http://tecnoesis.files.wordpress.com/2009/08/java-cross-platform-support.gif?w=346&h=332" style="border: 0px; margin: 0px; max-width: 600px; padding: 0px;" title="Java Cross Platform Support" width="346" /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> <br /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> <strong style="margin: 0px; padding: 0px;"><span style="color: #ff6600; margin: 0px; padding: 0px;">Java Platform:</span></strong></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> A <em style="margin: 0px; padding: 0px;">platform</em> is the hardware or software environment in which a program runs. Most platforms can be described as a combination of the operating system and underlying hardware. The Java platform differs from most other platforms in that it’s a software-only platform that runs on top of other hardware-based platforms.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> <br /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: center;"> <img alt="Java Platform Simplified" height="102" src="http://tecnoesis.files.wordpress.com/2009/08/java-platform-simplified.jpeg?w=221&h=102" style="border: 0px; margin: 0px; max-width: 600px; padding: 0px;" title="Java Platform Simplified" width="221" /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> <br /></div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> The Java platform has two components:</div> <ul style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin: 0px; padding: 0px 0px 10px; text-align: justify;"> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;">The <em style="margin: 0px; padding: 0px;">Java Virtual Machine</em></li> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;">The <em style="margin: 0px; padding: 0px;">Java Application Programming Interface</em> (API)</li> </ul> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> <em style="margin: 0px; padding: 0px;">Virtual Machine</em> is the base for the Java platform and is ported onto various hardware-based platforms.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> The <em style="margin: 0px; padding: 0px;">API</em> is a large collection of ready-made software components that provide many useful capabilities. It is grouped into libraries of related classes and interfaces; these libraries are known as <em style="margin: 0px; padding: 0px;">packages</em>.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> As a platform-independent environment, the Java platform can be a bit slower than native code. However, advances in compiler and virtual machine technologies are bringing performance close to that of native code without threatening portability. A <em style="margin: 0px; padding: 0px;">platform</em> is the hardware or software environment in which a program runs. We’ve already mentioned some of the most popular platforms like Microsoft Windows, Linux, Solaris OS, and Mac OS. Most platforms can be described as a combination of the operating system and underlying hardware. The Java platform differs from most other platforms in that it’s a software-only platform that runs on top of other hardware-based platforms.</div> <div style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin-bottom: 10px; padding: 0px; text-align: justify;"> The general-purpose, high-level Java programming language is a powerful software platform. Every full implementation of the Java platform gives you the following features:</div> <ul style="background-color: white; color: #555555; font-family: Verdana, 'BitStream vera Sans', Helvetica, sans-serif; font-size: 12px; line-height: 17px; margin: 0px; padding: 0px 0px 10px; text-align: justify;"> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;"><div style="margin: 0px; padding: 0px;"> <em style="margin: 0px; padding: 0px;">Development Tools</em>: The development tools provide everything you’ll need for compiling, running, monitoring, debugging, and documenting your applications. As a new developer, the main tools you’ll be using are the <code style="margin: 0px; padding: 0px;">javac</code> compiler, the <code style="margin: 0px; padding: 0px;">java</code> launcher, and the <code style="margin: 0px; padding: 0px;">javadoc</code>documentation tool.</div> </li> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;"><div style="margin: 0px; padding: 0px;"> Application Programming Interface <em style="margin: 0px; padding: 0px;">(API):</em> The API provides the core functionality of the Java programming language. It offers a wide array of useful classes ready for use in your own applications. It spans everything from basic objects, to networking and security, to XML generation and database access, and more. The core API is very large; to get an overview of what it contains, consult the <a href="http://java.sun.com/javase/6/docs/index.html" style="color: #2970a6; margin: 0px; padding: 0px; text-decoration: none;" target="_blank">Java SE Development Kit 6 (JDK<sup style="margin: 0px; padding: 0px;">TM</sup> 6) documentation</a>.</div> </li> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;"><div style="margin: 0px; padding: 0px;"> <em style="margin: 0px; padding: 0px;">Deployment Technologies:</em> The JDK software provides standard mechanisms such as the Java Web Start software and Java Plug-In software for deploying your applications to end users.</div> </li> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;"><div style="margin: 0px; padding: 0px;"> <em style="margin: 0px; padding: 0px;">User Interface Toolkits:</em> The Swing and Java 2D toolkits make it possible to create sophisticated Graphical User Interfaces (GUIs).</div> </li> <li style="list-style-position: inside; margin: 0px; padding: 0px 0px 0px 20px;"><div style="margin: 0px; padding: 0px;"> <em style="margin: 0px; padding: 0px;">Integration Libraries:</em> Integration libraries such as the Java IDL API, JDBC<sup style="margin: 0px; padding: 0px;">TM</sup> API, Java Naming and Directory Interface<sup style="margin: 0px; padding: 0px;">TM</sup> (“J.N.D.I.”) API, Java RMI, and Java Remote Method Invocation over Internet Inter-ORB Protocol Technology (Java RMI-IIOP Technology) enable database access and manipulation of remote objects.<br /> <div class="separator" style="clear: both; text-align: center;"> <br /></div> </div> </li> </ul> </div>

What is JVM ?

Each of the preceding buzzwords is explained in  The Java Language Environment  , a white paper written by James Gosling and Henry McGi...

Read more »

What is Java ? and Features of JAVA

<div dir="ltr" style="text-align: left;" trbidi="on"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody> <tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUU4U6PejiBEK0wGRh33LKGAA2qOtBfti-1SM6TwkC5HqhTxKCCX_sa9xDqkBFoPaiRULQMmwb4p8eludeDFG5fGvg9bI1UyDoXaILghW1Q6vhR6XExAs9krswkduRXDXENSkM96zUVuw/s1600/Java+featur1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUU4U6PejiBEK0wGRh33LKGAA2qOtBfti-1SM6TwkC5HqhTxKCCX_sa9xDqkBFoPaiRULQMmwb4p8eludeDFG5fGvg9bI1UyDoXaILghW1Q6vhR6XExAs9krswkduRXDXENSkM96zUVuw/s400/Java+featur1.jpg" width="400" /></a></td></tr> <tr><td class="tr-caption" style="text-align: center;"><h2> <span style="color: #0b5394; font-size: large;">Java features</span></h2> </td></tr> </tbody></table> <h3 style="text-align: left;"> <b><span style="background-color: white; font-family: Calibri, sans-serif;"><span style="color: #0b5394;">What is Java?</span></span></b></h3> <div class="MsoNormal" style="margin-left: .5in; mso-list: l17 level1 lfo11; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">u<span style="font-family: 'Times New Roman'; font-size: 7pt;"> </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Java is a programming language that:<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l17 level2 lfo11; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">n<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Is exclusively <b>object oriented</b><o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l17 level2 lfo11; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">n<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Has full <b>GUI support</b><o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l17 level2 lfo11; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">n<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Has full <b>network support</b><o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l17 level2 lfo11; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">n<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Is <b>platform independent</b><o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l17 level2 lfo11; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">n<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Executes <b>stand-alone or “on-demand” in web browser as applets</b><o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <h3 style="text-align: left;"> <b><span style="font-family: Calibri, sans-serif;"><span style="color: #0b5394;">Features of JAVA</span></span></b></h3> <ol start="1" style="margin-top: 0in;" type="1"> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Simple</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Secure</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Portable</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Object-oriented</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Robust</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Multithreaded</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Architecture-natural</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Interpreted</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">High performance</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Distributed</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><o:p></o:p></span></li> <li class="MsoNormal" style="mso-list: l12 level1 lfo1; tab-stops: list .5in; text-align: justify;"><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Dynamic</span></li> </ol> <h4> </h4> <h4> <ol start="1" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Simple</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l16 level1 lfo12; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Java was designed to be easy for the professional programmer to learn and use effectively.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l16 level1 lfo12; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Assuming that you have some programming experience, you will not find java hard to master.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l16 level1 lfo12; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">If you already understand the basic concepts of object oriented programming, learning java will be even easier.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l16 level1 lfo12; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">If you are an experienced C++ programmer, moving to java will require very little effort. Because java inherits the C/C++ syntax and many of the object oriented features of C++, most programmers have little trouble learning Java. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <h4> <ol start="2" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Security</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l13 level1 lfo13; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Security is the benefit of java. Java system not only verifies all memory access but also ensure that no viruses are communicated with an applet.<b> <o:p></o:p></b></span></div> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <h4 style="text-align: left;"> <b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">      3. <span style="color: #0b5394;">Portable</span></span></b></h4> <div class="MsoListParagraphCxSpFirst" style="margin-left: .25in; mso-add-space: auto; text-align: justify;"> <span style="font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Arial;">      The most significant contribution of java over other language is its portability.<o:p></o:p></span></div> <div class="MsoListParagraphCxSpMiddle" style="margin-left: .25in; mso-add-space: auto; text-align: justify;"> <span style="font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Arial;">      Java programs can be easily moved from one computer system to another.<o:p></o:p></span></div> <div class="MsoListParagraphCxSpMiddle" style="margin-left: .25in; mso-add-space: auto; text-align: justify;"> <span style="font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Arial;">      Java ensures portability in two ways:<o:p></o:p></span></div> <div class="MsoListParagraphCxSpMiddle" style="margin-left: .25in; mso-add-space: auto; text-align: justify;"> <span style="font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Arial;">      1. Java compiler generates byte code instruction that can be implemented on any machine.<o:p></o:p></span></div> <div class="MsoListParagraphCxSpLast" style="margin-left: .25in; mso-add-space: auto; text-align: justify;"> <span style="font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Arial;">      2.   The size of the primitive data types is <b>machine-independent</b>.<o:p></o:p></span></div> <h4> <ol start="4" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Object-Oriented</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <span style="font-family: Wingdings; text-indent: -24px;">v</span><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java is a true object oriented language. All <b>program code and data reside within object       and classes</b>. The object model in java is simple and easy to extend.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <h4> <ol start="5" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Robust(healthy, strong) </span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l13 level1 lfo13; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">The multiplatform environment of the Web places extraordinary demands on a program, because the program must execute reliably in a variety of systems. Thus, the ability to create robust programs was given a high priority in the design of java.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l13 level1 lfo13; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">To gain reliability, java has strict compile time and run time checking for codes.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; mso-list: l13 level1 lfo13; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">To better understand how java is robust, consider two main reasons for program failure: <b>memory management mistakes and mishandled exceptional conditions.</b><o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: 1.0in; text-align: justify;"> <br /></div> <h4> <ol start="6" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Multithreaded</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l3 level1 lfo14; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java was designed to meet the real-world requirement of creating interactive, networked programs. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l3 level1 lfo14; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">To accomplish this, java supports multithreaded programming, which allows you to write programs that do many things simultaneously. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l3 level1 lfo14; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">The java run-time system comes with an elegant yet sophisticated solution for multiprocess synchronization that enables you to construct smoothly running interactive systems. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l3 level1 lfo14; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java’s easy to use approach to multithreading allows you to think about the specific behavior of your program, not the multitasking subsystem. <o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <h4> <ol start="7" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Architecture-Neutral</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l0 level1 lfo15; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">A central issue of java programmers was that code longevity and portability. One of the main problems facing programmers is that no guarantee exists that if you write a program today, it will run tomorrow- even on the same machine. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l0 level1 lfo15; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Operating system upgrades, and changes in core system resources can al combine to make a program malfunction. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l0 level1 lfo15; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">The java designer made several hard decisions in the java language and the java virtual machine in an attempt to alter this situation. Their goal was “write once; run anywhere, any time, forever.”<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <h4> <ol start="8" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Interpreted </span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l11 level1 lfo16; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Usually a computer language is either compiled or interpreted. Java combines these approaches thus making java a two-stage system.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l11 level1 lfo16; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java compiler translates source code into byte code instructions. Byte codes are not machine instructions and so java interpreter generates machine code that can be directly executed by the machine that is running the java program.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l11 level1 lfo16; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">We can thus say that java is both a compiled and an interpreted language. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <h4> <ol start="9" style="margin-top: 0in;" type="1"> <li class="MsoNormal" style="mso-list: l4 level1 lfo8; tab-stops: list .5in; text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">High Performance</span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;">Java performance is impressive for an interpreted language, mainly due to the use    of intermediate byte code. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <h4> <ol start="10" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Distributed </span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l15 level1 lfo17; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java is designed for the distributed environment of the Internet, because it handles TCP/IP protocols. <o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l15 level1 lfo17; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java also supports <b>Remote Method Invocation (RMI).</b> This feature enables a program to invoke methods across a network.<o:p></o:p></span></div> <div class="MsoNormal" style="margin-left: .25in; text-align: justify;"> <br /></div> <h4> <ol start="11" style="margin-top: 0in; text-align: left;" type="1"> <li class="MsoNormal" style="text-align: justify;"><b><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial;"><span style="color: #0b5394;">Dynamic </span></span></b></li> </ol> </h4> <div class="MsoNormal" style="margin-left: .5in; text-align: justify;"> <br /></div> <div class="MsoNormal" style="margin-left: .75in; mso-list: l10 level1 lfo18; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java is capable of dynamically linking in new <b>class libraries, methods and object</b>.<o:p></o:p></span></div> <br /> <div class="MsoNormal" style="margin-left: .75in; mso-list: l10 level1 lfo18; text-align: justify; text-indent: -.25in;"> <!--[if !supportLists]--><span style="font-family: Wingdings; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">v<span style="font-family: 'Times New Roman'; font-size: 7pt;">  </span></span><!--[endif]--><span style="font-family: "Calibri","sans-serif"; mso-bidi-font-family: Arial; mso-bidi-font-weight: bold;">Java can also determine the type of class through a query, making it possible to either dynamically link or abort the program. <o:p></o:p></span></div> </div>

What is Java ? and Features of JAVA

Java features What is Java? u Java is a programming language that: n   Is exclusively object oriented n   Has full GUI suppor...

Read more »

Concept of Redirection and Piping in Unix

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="MsoNormal">  Most UNIX commands expect input to come from a file(s), and produce output to anther file(s).  “One of these files is the standard input, and is the place from which a program expects to read its input.  Another is called the standard output, and it is the file to which the program writes its results.  The third file is the diagnostic output (also called Standard error), and it is a file to which program writes any error responses.  Generally, the standard input is taken to be the keyboard (input is typed by the user), the standard output is the terminal screen.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <h2 style="text-align: left;"> <b><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><span style="color: #0b5394;">Concept of</span> </span></span></b><b><span style="font-family: 'Times New Roman', serif;"><span style="color: #0b5394; font-size: large;">Redirection</span></span></b></h2> <div> <b><span style="font-family: 'Times New Roman', serif;"><span style="color: #0b5394; font-size: large;"><br /></span></span></b></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPau7l8epyE72Lk4DZOpIjMfKG6I9t9n2MnqrKE5QH-kcG4IE4VIezvfi1SAQgC1hw2vsJ_Or7O1Hh2Vdto-YvQrNH4WCuhmy-sX706Lz2Zn9ajFHd_FPxzUldrNDW3Gm6OPiA1Xv2Khs/s1600/pipe_split.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="141" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPau7l8epyE72Lk4DZOpIjMfKG6I9t9n2MnqrKE5QH-kcG4IE4VIezvfi1SAQgC1hw2vsJ_Or7O1Hh2Vdto-YvQrNH4WCuhmy-sX706Lz2Zn9ajFHd_FPxzUldrNDW3Gm6OPiA1Xv2Khs/s400/pipe_split.png" width="400" /></a></div> <div> <b><span style="font-family: 'Times New Roman', serif;"><span style="color: #0b5394; font-size: large;"><br /></span></span></b></div> <div> <h3 style="text-align: left;"> <b>(1) Redirection Input:</b></h3> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             There are two possible sources of input for UNIX commands.  Programs such as ls and find get their input from the command line in the form of options and filenames.  Other programs, such as cat, can get their data from the standard input as well as from the command line.  Try the cat command with no options on the command line:<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$cat</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             There is no response.  Because n files are specified with the command, cat waits to get its input from your keyboard, the standard input file.  The program will accept input lines from the keyboard until it sees a line which begins with Ctrl+D, which is the end of file signal for standard input.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             To redirect the standard input, you use the<span style="color: #0b5394;"><b> <span style="font-family: Courier New, Courier, monospace;"><</span></b></span> operator.  For example, if you wanted cat to get its input from output.txt you could use the command.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$cat<output.txt</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             The difference between this command and<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$cat output.txt</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             is a subtle one.  In filenames provided as options to a command, you can use filename substitution.  When redirecting input, you must use the name of an existing file or device.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <h3 style="text-align: left;"> <b>(2) Redirection Output:</b></h3> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             Now, let’s say that you want to send the output of cat to a file, to save our shopping list on disk.  The shell lets you redirect standard output to a file name, by using the “<span style="color: #0b5394; font-family: Courier New, Courier, monospace;"><b>></b></span>” symbol.  Here’s how it works:<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$cat amg.txt>output.txt<o:p></o:p></span></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             The<b> </b><b style="color: #0b5394; font-family: 'Courier New', Courier, monospace;">></b> operator causes a new file to be created.  If you had already created a file named output.txt, it would be deleted and replaced with the new data.  If you wanted to add the new data to the old output, you could use the <span style="color: #0b5394; font-family: Courier New, Courier, monospace;"><b>>></b></span> operator.  For example.</div> <div class="MsoNormal"> <o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$cat amg.txt>>output.txt<o:p></o:p></span></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> </div> <div class="MsoNormal">             This will add content of amg.txt to output.txt file both file must be exists at specified path.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <br /></div> <h2 style="text-align: left;"> <b><span style="color: #0b5394;">Concept of Piping</span></b></h2> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRoMLCe3M2z-ttX_gHBQmEyhSQOK3ZuZa-rtdj8qmB3CFyRqFOQT3RerNERdHxG5lDV76Gmja34uYACinpTDgz_L9yMG2hIScsiDjUK6QM8P-xueYYxboMC9P-KD1WQHuXJs1JeiJs6sc/s1600/pipe4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="82" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRoMLCe3M2z-ttX_gHBQmEyhSQOK3ZuZa-rtdj8qmB3CFyRqFOQT3RerNERdHxG5lDV76Gmja34uYACinpTDgz_L9yMG2hIScsiDjUK6QM8P-xueYYxboMC9P-KD1WQHuXJs1JeiJs6sc/s400/pipe4.png" width="400" /></a></div> <div> <b><span style="color: #0b5394;"><br /></span></b></div> <div> <div class="MsoNormal"> Suppose that you wanted a directory listing that was sorted by the mode file type plus permissions.  To accomplish this, you might redirect the output from ls to a data file and then sort that data file.  For example.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$ls –l>tempfile</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$sort<tempfile</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   1024    Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Lines.dat<o:p></o:p></span></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   3072    Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Lines.idx<o:p></o:p></span></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   256      Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Pages.dat</span><span style="color: #bf9000;"><o:p></o:p></span></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             Although you get the result that you wanted, there are three drawback to this method:<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             You might end up with a lot of temporary file in your directory.  You would have to go back and remove them.  The sort program does not begins its work until the first command is complete.  This is not too significant with the small amount of data used in this example, but it can make a considerable difference with larger files.  The final output contains the name of your temp file, which might not be what you had in mind.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             Fortunately, there is a better way.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             The pipe symbol <b><span style="color: #0b5394;">(|)</span></b> causes the standard output of the program on the left side of the pipe to be passed directly to the standard input of the program on the right side of the pipe symbol.  Therefore, to get the same results as before, you can use the pipe symbol.  For example<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><span style="color: red; font-family: Courier New, Courier, monospace;">$ls –l|sort</span><o:p></o:p></b></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   1024    Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Lines.dat<o:p></o:p></span></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   3072    Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Lines.idx<o:p></o:p></span></div> <div class="MsoNormal"> <span style="color: #7f6000; font-family: Georgia, Times New Roman, serif;">-rw-rw-r-         1          marsha             adept   256      Jan 20 <st1:time hour="14" minute="14" w:st="on">14:14</st1:time> Pages.dat</span><o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">             To connect two or more operation within the same stream at that time pipe sign is used to perform such a operation in unix.<o:p></o:p></div> </div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <br /></div> </div> <div> <b><span style="font-family: 'Times New Roman', serif;"><span style="color: #0b5394; font-size: large;"><br /></span></span></b></div> </div>

Concept of Redirection and Piping in Unix

 Most UNIX commands expect input to come from a file(s), and produce output to anther file(s).  “One of these files is the standard input,...

Read more »

Useful Commands in Ubuntu

<div dir="ltr" style="text-align: left;" trbidi="on"> <span style="background-color: white; line-height: 22px;"><span style="font-family: inherit;">A comprehensive list of commands needed when using Ubuntu:</span></span><br /> <span style="background-color: white; line-height: 22px;"><span style="font-family: inherit;"><br /></span></span> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigwkv4pl6rg-Up8rRlhHqJSHu30sPAYeKJAAXURAneoEy0AWHKq3hMJbxZWyTwH8bQevAKiEL_5crgwJTbywgHf-xqZi1O1VTR_g690uKybod8vSoZXkli5TOcK_DRI2ZMGgwYWHTt3_4/s1600/images.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="97" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigwkv4pl6rg-Up8rRlhHqJSHu30sPAYeKJAAXURAneoEy0AWHKq3hMJbxZWyTwH8bQevAKiEL_5crgwJTbywgHf-xqZi1O1VTR_g690uKybod8vSoZXkli5TOcK_DRI2ZMGgwYWHTt3_4/s320/images.jpg" width="320" /></a></div> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <span style="background-color: white; line-height: 22px;"><span style="font-family: inherit;"><br /></span></span> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><span style="color: #0b5394;">Command privileges.</span></b><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> sudo command</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> - run command as root</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo su</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> –</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> root shellopen</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo su user </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– open shell as a user</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo -k</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – forget your password sudo</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">gksudo command </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– sudo visual dialog </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">(GNOME)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">kdesudo command</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – sudo visual dialog (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> sudo visudo</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – edit / etc / sudoers</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">gksudo nautilus </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– root file manager (GNOME)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">kdesudo konqueror </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– root file manager (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">passwd </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– change your password </span><br /> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><br style="border: none; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /><span style="color: #0b5394;">Command Network</span></b><span style="color: #0b5394;"><br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /></span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ifconfig </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– displays information network</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">iwconfig </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– displays information from wireless</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo iwlist scan</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – scan wireless networks</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo /etc/init.d/networking restart </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– reset the network</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">(file) /etc/network/interfaces</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – manual configuration</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> ifup interface</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – bring online interface</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ifdown interface </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– disable interface </span><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="color: #0b5394;"><b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Commands Display</b></span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo /etc/init.d/gdm restart</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – reset X (Gnome)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo /etc/init.d/kdm restart </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– reset X (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> (file) /etc/X11/xorg.conf</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – show Configuration</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">sudo dpkg-reconfigure</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> - reconfigure xserver-xorg-phigh - reset configuration X</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Ctrl+Alt+Bksp</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – X display reset if frozen</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Ctrl+Alt+FN</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – switch to tty N</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Ctrl+Alt+F7 </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– switch back to X display </span><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><span style="color: #0b5394;">Commands Service System.</span></b><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">start service </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– service to start work (Upstart)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">stop service </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– service to stop working (Upstart)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">status service</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – check if service is running (Upstart)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">/etc/init.d/service start</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – start service (SysV)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">/etc/init.d/service stop</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – stop service (SysV)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">/etc/init.d/service status</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – check service (SysV)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">/etc/init.d/service restart</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – reset service (SysV)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">runlevel </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– get current runlevel </span><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="color: #0b5394;"><b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Commands for Firewall.</b></span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw enable </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– turn on the firewall</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw disable</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – turn off the firewall</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw default allow </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– allow all connections by default</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> ufw default deny</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – drop all connections by default</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw status</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – current rules and</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw allow port</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – to allow traffic on port</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ufw deny port </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– port block</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> ufw deny from ip</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – ip block </span><br /> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><br style="border: none; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /><span style="color: #0b5394;">Command System.</span></b><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">lsb_release -a </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– get the version of Ubuntu</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">uname -r </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– get kernel version</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> uname -a </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– get all the information kernel </span><br /> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><br style="border: none; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /><span style="color: #0b5394;">Commands for Package Manager.</span></b><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> apt-get update</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – refresh updates available</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get upgrade</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – update all packages</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get dist-upgrade </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– version update</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get install pkg</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – installing pkg</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get remove pkg</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – uninstall pkg</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get autoremove</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – removing packages obsotletos</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">apt-get -f install –</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> try to fix packages</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">dpkg –configure -a</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – try to fix a broken package</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> dpkg -i pkg.deb</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – install file pkg.deb</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> (file) /etc/apt/sources.list </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– list of repositories APT </span><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="color: #0b5394;"><b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">Special Packages For commands.</b></span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> ubuntu-desktop </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– Setting the standard Ubuntu</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"> kubuntu-desktop</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> –KDE Desktop </span><span style="border: none; color: blue; font-family: inherit !important; font-size: inherit !important; list-style: none; margin: 0px; outline: none; padding: 0px; position: static; vertical-align: baseline;"><span class="kLink" style="background-image: none; border-bottom-style: solid; border-bottom-width: 1px; border-left-style: none !important; border-left-width: 0px !important; border-right-style: none !important; border-right-width: 0px !important; border-top-style: none !important; border-top-width: 0px !important; display: inline !important; float: none !important; font-family: inherit !important; font-size: inherit !important; list-style: none; margin: 0px; outline: none; padding: 0px 0px 1px !important; position: static; vertical-align: baseline; width: auto !important;"> </span></span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">xubuntu-desktop </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– desktop XFCE</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ubuntu-minimal</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – core earnings Ubuntu</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ubuntu-standard </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– the standard utilities Ubuntu</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">ubuntu-restricted-extras</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – not free, but useful</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    <span style="color: red;">kubuntu</span></span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">-restricted-extras </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– ditto KDE</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">   <span style="color: red;"> xubuntu</span></span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">-restricted-extras</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – ditto XFCE</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">build-essential</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – packages used to compile</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">linux-image-generic</span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;"> – latest generic kernel image</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">linux-headers-generic </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– latest headlines </span><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <b style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><span style="color: #0b5394;">Applications commands.</span></b><br /> <br style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">nautilus </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– File Manager (GNOME)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">dolphin </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– File Manager (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">konqueror </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– Web browser (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">kate </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– text editor (KDE)</span><br /> <span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">    </span><span style="border: none; color: red; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;">gedit </span><span style="background-color: white; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px;">– text editor (GNOME)</span><span style="border: none; font-family: 'Lithos Pro', tahoma, Verdana, Arial, sans-serif; font-size: 12px; line-height: 22px; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;"><br style="border: none; list-style: none; margin: 0px; outline: none; padding: 0px; vertical-align: baseline;" /></span></div>

Useful Commands in Ubuntu

A comprehensive list of commands needed when using Ubuntu: Command privileges.      sudo command  - run command as root      sudo...

Read more »