Change the applet in Listing 6.24 so that after the button is clicked, the button disappears. The label and the icon should remain visible just as in Listing 6.24. Hint: This is not a big change.

listing 6.24

import javax.swing.ImageIcon; import javax.swing.JApplet; import javax.swing.JButton; import javax.swing.JLabel; import java.awt.Color; import java.awt.Container; import java.awt.FlowLayout; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; /** Simple demonstration of changing visibility in an applet. */ public class VisibilityDemo extends JApplet implements ActionListener { private JLabel response; private Container contentPane; public void init( ) { contentPane = getContentPane( ); contentPane.setBackground(Color.WHITE); //Create button: JButton aButton = new JButton("Push me!"); aButton.addActionListener(this); //Create label: response = new JLabel("Thanks. That felt good!"); ImageIcon smileyFaceIcon = new ImageIcon("smiley.gif"); response.setIcon(smileyFaceIcon); response.setVisible(false);//Invisible until button is clicked //Add button: contentPane.setLayout(new FlowLayout( )); contentPane.add(aButton); //Add label contentPane.add(response); } public void actionPerformed(ActionEvent e) { contentPane.setBackground(Color.PINK); response.setVisible(true);//Show label } } 

helpful files to make it easier

import javax.swing.JApplet; import javax.swing.JButton; import javax.swing.ImageIcon; import java.awt.Color; import java.awt.Container; import java.awt.FlowLayout; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; /** Simple demonstration of putting buttons in an Applet. These buttons do something when clicked. */ public class ButtonIconDemo2 extends JApplet implements ActionListener { public void init( ) { Container contentPane = getContentPane( ); contentPane.setBackground(Color.WHITE); contentPane.setLayout(new FlowLayout( )); JButton sunnyButton = new JButton("Sunny"); ImageIcon smileyFaceIcon = new ImageIcon("smiley.gif"); sunnyButton.setIcon(smileyFaceIcon); contentPane.add(sunnyButton); sunnyButton.addActionListener(this); JButton cloudyButton = new JButton("Cloudy"); ImageIcon nastyFaceIcon = new ImageIcon("nasty.gif"); cloudyButton.setIcon(nastyFaceIcon); contentPane.add(cloudyButton); cloudyButton.addActionListener(this); } public void actionPerformed(ActionEvent e) { Container contentPane = getContentPane( ); if (e.getActionCommand( ).equals("Sunny")) contentPane.setBackground(Color.BLUE); else if (e.getActionCommand( ).equals("Cloudy")) contentPane.setBackground(Color.GRAY); else System.out.println("Error in button interface."); } } 

odd or even

import java.util.Scanner; class OddOrEven { public static void main(String args[]) { int x; System.out.println("Enter an integer to check if it is odd or even "); Scanner in = new Scanner(System.in); x = in.nextInt(); if ( x % 2 == 0 ) System.out.println("You entered an even number."); else System.out.println("You entered an odd number."); } } 

light applet

/* * LightApplet.java * * Created on March 13, 2007, 1:44 PM * * Solution to Project 14 */ import javax.swing.*; import java.awt.*; import java.awt.event.*; /** * * @author charleshoot */ public class LightApplet extends javax.swing.JApplet implements ActionListener { private boolean isOn; private JButton onOffButton; private Container contentPane; public void init() { isOn = false; contentPane = getContentPane(); contentPane.setBackground(Color.DARK_GRAY); //Program button: onOffButton = new JButton("On/Off"); onOffButton.addActionListener(this); //Add button: contentPane.setLayout(new BorderLayout()); contentPane.add(onOffButton, BorderLayout.NORTH); } public void actionPerformed(ActionEvent e) { if(e.getActionCommand().equals("On/Off") ){ isOn = !isOn; if(isOn) contentPane.setBackground(Color.YELLOW); else contentPane.setBackground(Color.DARK_GRAY); } } } 

More About objects and Methods Label That Changes with a LISTING 6.24 Visibility Part 2 of 2) Applet output Initially visibility Demo Applet Viewer Applet Output After Clicking Button Applet Viewer Visibility Demo X when the user clicks the button, the method actionPerformed is invoked. This method executes the statement response se visible Ctrue)