Write java code to design the following graphical user interface with main window having background color blue. The interface should contain 3 buttons for 'Yellow', 'red' and 'pink' When a button is clicked the background color of JTextArea found at the center of main window(JFrame) should be changed to that color.

Answer 1

To create a Java graphical user interface (GUI) as described, you can use the Swing library. Below is a sample code that sets up a JFrame with a blue background and three buttons ("Yellow", "Red", and "Pink"). When you click a button, the background color of a JTextArea in the center of the main window changes to the corresponding color.

Here's the complete code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ColorChanger extends JFrame {
    private JTextArea textArea;

    public ColorChanger() {
        // Set the title of the JFrame
        setTitle("Color Changer");

        // Set the default close operation
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Set the layout manager
        setLayout(new BorderLayout());

        // Create a JTextArea and set its properties
        textArea = new JTextArea("Click a button to change my background color");
        textArea.setEditable(false);
        textArea.setBackground(Color.WHITE); // Initial background color
        add(textArea, BorderLayout.CENTER);

        // Create a JPanel to hold buttons
        JPanel buttonPanel = new JPanel();
        buttonPanel.setBackground(Color.BLUE); // Panel background will be blue
        
        // Create buttons for different colors
        JButton yellowButton = new JButton("Yellow");
        JButton redButton = new JButton("Red");
        JButton pinkButton = new JButton("Pink");

        // Add action listeners for buttons
        yellowButton.addActionListener(new ColorAction(Color.YELLOW));
        redButton.addActionListener(new ColorAction(Color.RED));
        pinkButton.addActionListener(new ColorAction(Color.PINK));

        // Add buttons to the button panel
        buttonPanel.add(yellowButton);
        buttonPanel.add(redButton);
        buttonPanel.add(pinkButton);

        // Add button panel to the frame
        add(buttonPanel, BorderLayout.SOUTH);

        // Set the background color of the main window
        getContentPane().setBackground(Color.BLUE);

        // Set the window size and make it visible
        setSize(400, 300);
        setVisible(true);
        setLocationRelativeTo(null); // Center the window on the screen
    }

    // Action listener class to change the background color of the JTextArea
    private class ColorAction implements ActionListener {
        private Color color;

        public ColorAction(Color color) {
            this.color = color;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            textArea.setBackground(color);
        }
    }

    // Main method to run the application
    public static void main(String[] args) {
        // Use SwingUtilities to ensure thread safety
        SwingUtilities.invokeLater(ColorChanger::new);
    }
}

Explanation:

1. JFrame: The main window which contains all the components.
2. JTextArea: A text area in the center to display information and change colors.
3. JPanel: A panel to hold the buttons at the bottom.
4. JButton: Three buttons to change the background color to Yellow, Red, and Pink.
5. ActionListener: When a button is clicked, it changes the background color of the JTextArea using the setBackground() method.
6. setLayout(): Used to set the layout of the JFrame.
7. setSize() and setVisible(): Methods to set the dimensions of the window and to make it visible.

To run this code:

• Copy and paste it into a Java IDE or a text file with a .java extension.
• Compile and run the program to see the GUI in action.