Category: Java/J2EE/J2ME

/* The following code example is taken from the book  * “The C++ Standard Library – A Tutorial and Reference”  * by Nicolai M. Josuttis, Addison-Wesley, 1999  *  * (C) Copyright Nicolai M. Josuttis 1999.  * Permission to copy, use, modify, sell and distribute this software  * is granted provided this copyright notice appears in …

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&&&&&&&&&&&&&&&&&&& Example demonstrating the use of packages.     * Class1.java defined in package1.     * Class2.java defined in package2.     * Class3.java defined in package2.package3.     * Class1.java defined in package4.     * PackageExample.java Driver for package example &&&&&&&&&&&&&&&&&&&&& ~~~~~~~~~~~~~~~~~~~~~ Class1.java defined in package1. ~~~~~~~~~~~~~~~~~~~~~ package package1; *****************   public class Class1 {   public …

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**************************** Code examples for interfaces:     * Class1.java implements Interface1.java     * Abstract Class2.java implements Interface1.java and Interface2.java     * Class3.java extends abstract class Class2.java     * Interface3.java extends Interface1.java and Interface2.java *************************** ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Class1.java ~~~~~~~~~~~~~~~~~~~~~~~~~~~ // This class is not abstract, so it must provide // implementations of method1 and method2. public class Class1 …

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************************ Ship.java A Ship class illustrating object-oriented programming concepts. Incorporates Javadoc comments. See ShipTest.java for a test. ************************ /** Ship example to demonstrate OOP in Java.  *  *  @author  *          Larry Brown  *  @version 2.0  */ public class Ship {   // Instance variables   private double x=0.0, y=0.0, speed=1.0, direction=0.0;   private String name; …

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Test1.java Accesses instance variables in a Ship object. ******************************************************** // Create a class with five instance variables (fields): // x, y, speed, direction, and name. Note that Ship1 is // not declared “public”, so it can be in the same file as // Test1. A Java file can only contain one “public” class // definition. …

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****************** ShowArgs.java Application that reports all command-line arguments. ******************  */ public class ShowArgs {   public static void main(String[] args) {     for(int i=0; i

DropBall.java Uses a while loop to determine how long it takes a ball to fall from the top of the Washington Monument to the ground ************************************************************ /** Simulating dropping a ball from the top of the Washington  *  Monument. The program outputs the height of the ball each  *  second until the ball hits the …

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import java.text.*; /** Formatting real numbers with DecimalFormat.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ public class NumFormat {   public static void main (String[] args) {     DecimalFormat …

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/** Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ import java.awt.Point; public class ModificationTest extends ReferenceTest {   public static void main(String[] args) {     Point p1 = new Point(1, 2); // …

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/** Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ interface Barking {} class Mammal {} class Canine extends Mammal {} class Dog extends Canine implements Barking {} class Retriever extends Dog {} …

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/** Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.    */    // Further simplified getURL method.    public URL getURL() {     if (url != null) {       return(url);     }     …

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/** A test of the Exec class.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ public class ExecTest {   public static void main(String[] args) {     // Note: no …

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/** Simulating dropping a ball from the top of the Washington  *  Monument. The program outputs the height of the ball each  *  second until the ball hits the ground.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown; …

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JavaMan1.java Applet that loads an image from a relative URL. ************************************************************* import java.applet.Applet; import java.awt.*; /** An applet that loads an image from a relative URL.  * >>>>>>>>>>>>>>>>>>> public class JavaMan1 extends Applet {   private Image javaMan;   public void init() {     javaMan = getImage(getCodeBase(),”images/Java-Man.gif”);   }   public void paint(Graphics g) { …

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AppletTemplate.java >>>>>>>>>>>>>>>>>>>> import java.applet.Applet; import java.awt.*; ******************** public class AppletTemplate extends Applet {   // Variable declarations.   public void init() {     // Variable initializations, image loading, etc.   }   public void paint(Graphics g) {     // Drawing operations.   } } >>>>>>>>>>>>>>>>>>>>>

ForwardSnippet.java Partial servlet illustrating how to use a RequestDispatcher to forward requests public void doGet(HttpServletRequest request,                   HttpServletResponse response)     throws ServletException, IOException {   String operation = request.getParameter(“operation”);   if (operation == null) {     operation = “unknown”;   }   if (operation.equals(“operation1”)) {     gotoPage(“/operations/presentation1.jsp”,              request, response);   } else if (operation.equals(“operation2”)) …

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*********************************** # Example illustrating inheritance and abstract classes.     * Shape.java The parent class (abstract) for all closed, open, curved, and straight-edged shapes.     * Curve.java An (abstract) curved Shape (open or closed).     * StraightEdgedShape.java A Shape with straight edges (open or closed).     * Measurable.java Interface defining classes with measurable areas.     * …

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***************************** Speedboat.java Illustrates inheritance from Ship class. See SpeedboatTest.java for a test. ***************************** /** A fast Ship. Red and going 20 knots by default.  *  *********************** public class Speedboat extends Ship {   private String color = “red”;   /** Builds a red Speedboat going N at 20 knots. */     public Speedboat(String name) …

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********************* class Ship4 {   public double x=0.0, y=0.0, speed=1.0, direction=0.0;   public String name;   // This constructor takes the parameters explicitly.     public Ship4(double x, double y, double speed,                double direction, String name) {     this.x = x;     this.y = y;     this.speed = speed;     this.direction = direction;     …

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********************* import java.applet.Applet; import java.awt.*; *********************   public class HelloWWW extends Applet {   private int fontSize = 40;     public void init() {     setBackground(Color.black);     setForeground(Color.white);     setFont(new Font(“SansSerif”, Font.BOLD, fontSize));   }     public void paint(Graphics g) {     g.drawString(“Hello, World Wide Web.”, 5, fontSize+5);   } } <<<<<<<<<<<<<<<<<<<<<

******************* HelloWorld.java Basic Hello World application. *******************  */ public class HelloWorld {  public static void main(String[] args) {     System.out.println(“Hello, world.”);   } } /*

/** Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */   public class StringTest {   public static void main (String[] args) {     String str = “”;     if (args.length > 0) …

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import java.io.*; /** Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ public class NegativeLengthException extends Exception {   /** Test NegativeLengthException */   public static void main(String[] args) {     try { …

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Treetest.java /** A NodeOperator that prints each node.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ class PrintOperator implements NodeOperator {   public void operateOn(Node node) {     System.out.println(node.getNodeValue());   …

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/** Report on a round of golf at St. Andy?s.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ public class Golf {   public static void main(String[] args) {     …

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import java.math.BigInteger; /** Computes an exact factorial, using a BigInteger.  *  *  Taken from Core Web Programming from  *  Prentice Hall and Sun Microsystems Press,  *  .  *  © 2001 Marty Hall and Larry Brown;  *  may be freely used or adapted.  */ public class Factorial {   public static void main(String[] args) {     …

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import java.io.*; /** A class that eases the pain of running external processes  *  from applications. Lets you run a program three ways:  *        *          exec: Execute the command, returning      *         immediately even if the command is still running.      *         This would be appropriate for printing a file.      …

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~~~~~~~~~~~~~~~~~~~ ImageBox.java A class that incorrectly tries to load an image and draw an outline around it. The problem is that the size of the image is requested before the image is completely loaded, thus, returning a width and height of -1. ~~~~~~~~~~~~~~~~~~~ import java.applet.Applet; import java.awt.*; /** A class that incorrectly tries to load …

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HelloWWW2.java Illustrates the ability of an applet to read parameters contained in the HTML document (PARAM element containing a NAME-VALUE pair). &&&&&&&&&&&&&&&&&&&&&&&&&&&&&& import java.applet.Applet; import java.awt.*; ************************* public class HelloWWW2 extends Applet {   public void init() {     setFont(new Font(“SansSerif”, Font.BOLD, 30));     Color background = Color.gray;     Color foreground = Color.darkGray;     String …

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quick-search.html Front end to travel site <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Front end to travel servlet. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD>   <TITLE>Online Travel Quick Search</TITLE>   <LINK REL=STYLESHEET         HREF=”travel-styles.css”         …

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IfExample.jsp Page that uses the custom nested tags <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of IfTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>If Tag Example</TITLE> <LINK REL=STYLESHEET       HREF=”JSP-Styles.css”       TYPE=”text/css”> </HEAD> …

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*/ public class Statics {  public static void main(String[] args) {     staticMethod();     Statics s1 = new Statics();     s1.regularMethod();   }   public static void staticMethod() {     System.out.println(“This is a static method.”);   }   public void regularMethod() {     System.out.println(“This is a regular method.”);   } }

import java.applet.Applet; import java.awt.*; /././././././ public class Buttons extends Applet {   private Button button1, button2, button3;     public void init() {     button1 = new Button(“Button One”);     button2 = new Button(“Button Two”);     button3 = new Button(“Button Three”);     add(button1);     add(button2);     add(button3);   } } /././././././././.

IfTag.java, IfConditionTag.java, IfThenTag.java, and IfElseTag.java, Custom tags that make use of tag nesting IfTag.java package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; import javax.servlet.*; /** A tag that acts like an if/then/else.  *  <P>  *  Taken from Core Web Programming Java 2 Edition  *  from Prentice Hall and Sun Microsystems Press,  *  .  *  May …

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FilterExample.jsp Page that uses the FilterTag custom tag <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of FilterTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>HTML Logical Character Styles</TITLE> <LINK REL=STYLESHEET       HREF=”JSP-Styles.css”       TYPE=”text/css”> …

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^^^^^^^^^^^^^^^^^ TiledImages.java Demonstrates using a TexturePaint to fill an shape with a tiled image. Uses the following class and images:     * ImageUtilities.java Simplifies creating a BufferedImage from an image file. ~~~~~~~~~~~~~~~~~~ import javax.swing.*; import java.awt.*; import java.awt.geom.*; import java.awt.image.*; /** An example of using TexturePaint to fill objects with tiled  *  images. Uses the …

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import javax.swing.*;   // For JPanel, etc. import java.awt.*;      // For Graphics, etc. import java.awt.geom.*; // For Ellipse2D, etc. /** An example of drawing/filling shapes with Java 2D in  *  Java 1.2 and later.  * ************************** public class ShapeExample extends JPanel {   private Ellipse2D.Double circle =     new Ellipse2D.Double(10, 10, 350, 350);   private Rectangle2D.Double …

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import java.applet.Applet; import java.awt.*; /** Lets the user enter the name of any  *  good programming language. Or does it?  *    ********************* public class JavaTextField extends Applet {   public void init() {     setFont(new Font(“Serif”, Font.BOLD, 14));     setLayout(new GridLayout(2, 1));     add(new Label(“Enter a Good Programming Language”,                   Label.CENTER));     LanguageField langField …

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import java.applet.Applet; import java.awt.*; import java.awt.event.*; /** Prints non-detailed reports of mouse events.  *  Uses the low-level processXxxEvent methods instead  *  of the usual event listeners.  *    ***************** public class MouseReporter extends Applet {   public void init() {     setBackground(Color.blue); // So you can see applet in page     enableEvents(AWTEvent.MOUSE_EVENT_MASK |                  AWTEvent.MOUSE_MOTION_EVENT_MASK); …

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HeadingExample.jsp Page that uses the HeadingTag custom tag <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of HeadingTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>Some Tag-Generated Headings</TITLE> </HEAD> <BODY> <%@ taglib uri=”cwp-taglib.tld” prefix=”cwp” %> …

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PrimeExample.jsp Page that uses the PrimeTag custom tag <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of PrimeTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>Some N-Digit Primes</TITLE> <LINK REL=STYLESHEET       HREF=”JSP-Styles.css”       TYPE=”text/css”> </HEAD> …

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SimplePrimeExample.jsp Page that uses the SimplePrimeTag custom tag <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of SimplePrimeTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>Some 50-Digit Primes</TITLE> <LINK REL=STYLESHEET       HREF=”JSP-Styles.css”       TYPE=”text/css”> </HEAD> …

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SimpleExample.jsp Page that uses the ExampleTag custom tag. <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of very simple JSP custom tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <%@ taglib uri=”cwp-taglib.tld” prefix=”cwp” %> <TITLE><cwp:example /></TITLE> …

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ExampleTag.java Very simple custom tag. Remember to install it in the WEB-INF/classes/cwp/tags directory. package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; /** Very simple JSP tag that just inserts a string  *  (“Custom tag example…”) into the output.  *  The actual name of the tag is not defined here;  *  that is given by the …

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AccessCountBean.java Bean used to illustrate the difference between running jsp:setProperty for every request vs. only when the object is created package cwp; /** Simple bean to illustrate sharing beans through  *  use of the scope attribute of jsp:useBean.  *  <P>  *  Taken from Core Web Programming Java 2 Edition  *  from Prentice Hall and Sun …

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SaleEntry2.jsp Page that uses the SaleEntry bean, using the param attribute to read request parameters and assign them to bean properties <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Example of using jsp:setProperty and an explicity association with an input parameter. See SaleEntry1.jsp and SaleEntry3.jsp for alternatives.     Taken from Core Web Programming Java …

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package cwp; /** Simple bean to illustrate the various forms  *  of jsp:setProperty.  *  <P>  *  Taken from Core Web Programming Java 2 Edition  *  from Prentice Hall and Sun Microsystems Press,  *  .  *  May be freely used or adapted.  */ public class SaleEntry {   private String itemID = “unknown”;   private double …

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import java.net.*; import java.io.*; /** When this class is built, it returns a value  *  immediately, but this value returns false for isDone  *  and null for getQueries. Meanwhile, it starts a Thread  *  to request an array of query strings from the server,  *  reading them in one fell swoop by means of an …

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SearchSpec.java ******************* /** Small class that encapsulates how to construct a  *  search string for a particular search engine.  *  Taken from Core Web Programming Java 2 Edition  *  from Prentice Hall and Sun Microsystems Press,  *  May be freely used or adapted.  */ public class SearchSpec {   private String name, baseURL, numResultsSuffix;   …

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# DebugExample.jsp Page that uses the DebugTag custom tag <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> <!– Illustration of SimplePrimeTag tag. Taken from Core Web Programming Java 2 Edition from Prentice Hall and Sun Microsystems Press, . May be freely used or adapted. –> <HTML> <HEAD> <TITLE>Using the Debug Tag</TITLE> <LINK REL=STYLESHEET       HREF=”JSP-Styles.css”       …

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import javax.swing.*; import java.awt.*; import java.awt.geom.*; /** An example of shear transformations on a rectangle.  *  *********************** public class ShearExample extends JPanel {   private static int gap=10, width=100;   private Rectangle rect = new Rectangle(gap, gap, 100, 100);   public void paintComponent(Graphics g) {     super.paintComponent(g);     Graphics2D g2d = (Graphics2D)g;     for (int …

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import javax.swing.*; import java.awt.*; import java.awt.geom.*; /** A demonstration of different controls when joining two line  *  segments. The style of the line end point is controlled  *  through the capStyle parameter.  *  ************************************ public class LineStyles extends JPanel {   private GeneralPath path;   private static int x = 30, deltaX = 150, y …

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import java.awt.*; /** An example of using local fonts to perform drawing in  *  Java 2D.  *  ********************** public class FontExample extends GradientPaintExample {   public FontExample() {     GraphicsEnvironment env =       GraphicsEnvironment.getLocalGraphicsEnvironment();     env.getAvailableFontFamilyNames();     setFont(new Font(“Goudy Handtooled BT”, Font.PLAIN, 100));   }   protected void drawBigString(Graphics2D g2d) {     g2d.setPaint(Color.black);     g2d.drawString(“Java …

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GradientPaintExample.java Draws a circle with a gradient fill. Inherits from ShapeExample.java. ************************************** import java.awt.*; /** An example of applying a gradient fill to a circle. The  *  color definition starts with red at (0,0), gradually  *  changing to yellow at (175,175).  *  ********************************** public class GradientPaintExample extends ShapeExample {   private GradientPaint gradient =     …

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import java.applet.Applet; import java.awt.*; import java.awt.event.*; /** An applet that lets you perform freehand drawing.  *    **************** public class SimpleWhiteboard extends Applet {   protected int lastX=0, lastY=0;   public void init() {     setBackground(Color.white);     setForeground(Color.blue);     addMouseListener(new PositionRecorder());     addMouseMotionListener(new LineDrawer());   }   protected void record(int x, int y) {     …

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import java.awt.*; import java.awt.event.*; /** A spelling-correcting TextField for entering  *  a language name.  *    ******************* public class LanguageField extends TextField {   private String[] substrings =     { “”, “J”, “Ja”, “Jav”, “Java” };   public LanguageField() {     addKeyListener(new SpellingCorrector());     addActionListener(new WordCompleter());     addFocusListener(new SubliminalAdvertiser());   }   // Put caret …

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DebugTag.java Custom tag that optionally makes use of a tag body package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; import javax.servlet.*; /** A tag that includes the body content only if  *  the “debug” request parameter is set.  *  <P>  *  Taken from Core Web Programming Java 2 Edition  *  from Prentice Hall and Sun …

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HeadingTag.java Custom tag that makes use of a tag body package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; /** Generates an HTML heading with the specified background  *  color, foreground color, alignment, font, and font size.  *  You can also turn on a border around it, which normally  *  just barely encloses the heading, but …

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PrimeTag.java Custom tag that outputs a random prime number of a user-specifiable approximate length package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; /** Generates an N-digit random prime (default N = 50).  *  Extends SimplePrimeTag, adding a length attribute  *  to set the size of the prime. The doStartTag  *  method of the parent class …

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SimplePrimeTag.java Custom tag that outputs a random prime number of a fixed approximate length package cwp.tags; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import java.io.*; import java.math.*; import cwp.*; /** Generates a prime of approximately 50 digits.  *  (50 is actually the length of the random number  *  generated — the first prime above that number will  *  …

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