Demo02 : Event Handling

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

public class Demo02 extends JFrame
        implements ActionListener{

  private JButton btn1, btn2;
  private JPanel northPanel;

  public Demo02(){
    btn1 = new JButton("Button 1");
    btn2 = new JButton("Button 2");
    northPanel = new JPanel();
    northPanel.add(btn1);
    northPanel.add(btn2);
    getContentPane().add(northPanel, 
                         BorderLayout.NORTH);
    // Step 4: 
    btn1.addActionListener(this);
    btn2.addActionListener(this);
  }//end constructor


  // Step 3: add this method
  public void actionPerformed(ActionEvent ev){
    if (ev.getSource() == btn1)
        JOptionPane.showMessageDialog(null,
             "Hi,you clicked button 1");
    else if (ev.getSource() == btn2){
      JOptionPane.showMessageDialog(null,
             "Hi,you clicked button 2");
    }
  }//end actionPerformed


}//end class