Question

22. Fill in the codes that creates a Java GUI application that contains a label and a button. The label reads "Click the button to change the background color." When the button is clicked, the background is changed to a red color. The program produces the following output. Point 7 22.1 package javaapplication 179; import javax.swing": import java.ant": import java.awt.exst. public class ColorChange extends JFrame / not allowed to change JLabel label - new JLabel("Click the button to change the background color"); JButton button - new JButton("Change Color"); public ColorChange 0 super("Change color"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); set Layout(new FlowLayout); add(tabel): add(button) 1/ your codes go here

Answer 1

package javaapplication179; import javax.swing. *; import java.awt. *; import java.awt.event.*; class ColorChange extends JFrame implements ActionListener { JLabel label = new JLabel("Click the button to change the background color"); JButton button = new JButton("Change Color"); public ColorChange() { super("Change color"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; setLayout(new FlowLayout()); button.addActionListener(this); /*The above line of code adds an action listener to the JButton button */

add(label); add(button); } /*Since a listener to button is added, on the click of the button, this actionPerformed() method is called. */ public void actionPerformed (ActionEvent e) { this.getContentPane().setBackground (Color.RED); /*The above line of code change the background color of the JFrame, ColorChange to red. The keyword this specifies the current frame, ColorChange. */ } }

package javaapplication179; public class JavaApplication179 { public static void main(String a[]) { ColorChange aFrame = new ColorChange(); final int WIDTH=250; final int HEIGHT=100; aFrame.setSize(WIDTH, HEIGHT); aFrame.setVisible(true); } }

package javaapplication179;

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;



class ColorChange extends JFrame implements ActionListener 

{

      JLabel label = new JLabel("Click the button to change the background color");

      JButton button = new JButton("Change Color");



      public ColorChange()

      {

            super("Change color");

            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            setLayout(new FlowLayout());

            button.addActionListener(this);

            /*The above line of code adds an action listener to the JButton button */ 

            add(label);

            add(button);

            }



            /*Since a listener to button is added, on the click of the button, this actionPerformed( ) method is called. */

            public void actionPerformed(ActionEvent e) 

            {

                        this.getContentPane().setBackground(Color.RED); 

                        /*The above line of code change the background color of the JFrame, ColorChange to red. 

                            The keyword this specifies the current frame, ColorChange. */

            }

}



package javaapplication179;

public class JavaApplication179
{

            public static void main(String a[])

            {

                        ColorChange aFrame = new ColorChange();

                        final int WIDTH=250;

                        final int HEIGHT=100;

                        aFrame.setSize(WIDTH,HEIGHT);

                        aFrame.setVisible(true);

            }

}