简单的GUI程序

Question

I just made this program that I add a button on my panel, but I am not able to move on to use actionListener to make the button work. Their should be pictures appered on the panel and when the button clicked, the picture should change to another picture. Please help me, thanks! Here is my code.

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

public class DrawPanelThree extends JPanel
{
    private JButton button;

    public DrawPanelThree()
    {
        button = new JButton();
        setLayout(new BorderLayout());
        add(button, BorderLayout.SOUTH);
        button.setText("Start");
    }

    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.drawRect(90, 40, 100, 50);
        g.setColor(Color.RED);
        g.fillRect(10, 10, 10, 10);
        g.fillRect(260, 10, 10, 10);
        g.fillRect(10, 120, 10, 10);
        g.fillRect(260, 120, 10, 10);
        g.setColor(new Color(255, 215, 0));
        g.fillOval(120, 45, 40, 40);
    }

    public static void main(String[] args)
    {
        JFrame frame = new JFrame();
        frame.setTitle("Rectangle");
        frame.setSize(new Dimension(300, 200));
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        DrawPanelThree panel = new DrawPanelThree();
        frame.add(panel);
        panel.setBackground(Color.CYAN);

        frame.setVisible(true);
    }

    private class ButtonListener implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {

        }
    }
}

Answer 1

You have to add the ActionListener to the button, like so:

button.addActionListener(new MyCoolActionListener());

You can also define the ActionListener when you declare it, but that's the general idea. You want to add the ActionListener soon after you declare the JButton , in your constructor.

Hope this helps!