Java 请问我只想在点击b2的时候弹出dialog 该如何实现？

package week10;
import javax.swing.*;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

public class ButtonDemo extends JPanel implements ActionListener {
    protected JButton b1, b2, b3;

    public ButtonDemo() {

        b1 = new JButton("Disable middle button");
        b1.setVerticalTextPosition(AbstractButton.CENTER);
        b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales
        b1.setMnemonic(KeyEvent.VK_D);
        b1.setActionCommand("disable");

        b2 = new JButton("Middle button");
        b2.setVerticalTextPosition(AbstractButton.BOTTOM);
        b2.setHorizontalTextPosition(AbstractButton.CENTER);
        b2.setMnemonic(KeyEvent.VK_M);

        b3 = new JButton("Enable middle button");

        b3.setActionCommand("enable");
        b3.setEnabled(false);

        b1.addActionListener(this);
        b2.addActionListener(this);
        b3.addActionListener(this);

        b1.setToolTipText("Click this button to disable the middle button.");
        b2.setToolTipText("This middle button does nothing when you click it.");
        b3.setToolTipText("Click this button to enable the middle button.");

        add(b1);
        add(b2);
        add(b3);
    }

    public void actionPerformed(ActionEvent e) {
        if ("disable".equals(e.getActionCommand())) {
            b2.setEnabled(false);
            b1.setEnabled(false);
            b3.setEnabled(true);
        } else {
            b2.setEnabled(true);
            b1.setEnabled(true);
            b3.setEnabled(false);
        }
            javax.swing.JOptionPane.showMessageDialog(null,"dialog");

    }

    protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = ButtonDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    private static void createAndShowGUI() {

        JFrame frame = new JFrame("ButtonDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        ButtonDemo newContentPane = new ButtonDemo();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

我只想在点击b2的时候弹出dialog 但现在是点击每一个按钮都会弹出窗口 请问该如何改才能实现？

加if判断
if(e.getSource() == b2){

public void actionPerformed(ActionEvent e) {
        if ("disable".equals(e.getActionCommand())) {
            b2.setEnabled(false);
            b1.setEnabled(false);
            b3.setEnabled(true);
        } else {
            b2.setEnabled(true);
            b1.setEnabled(true);
            b3.setEnabled(false);
        }
        if(e.getSource() == b2){
            javax.swing.JOptionPane.showMessageDialog(null,"dialog");
       }
    }