Message Box in Java

Display a Message box in Java on Button Click.

import java.awt.*;
import java.awt.event.*;

public class messageBox extends Dialog
{
  Button b1,b2;
  messageBox(Frame fm,String lab)
  {
    super(fm,"Message",true);
    setLayout(new GridLayout(2,1,0,0));

    Panel p1 = new Panel();
    Panel p2 = new Panel();

    p1.setLayout(new FlowLayout(FlowLayout.CENTER,20,15));
    p2.setLayout(new FlowLayout(FlowLayout.CENTER,20,15));

    p1.add(new Label(lab));

    b1 = new Button("Ok");
    b1.addActionListener(new B1());
    p2.add(b1);

    b2 = new Button("Cancel");
    b2.addActionListener(new B1());
    p2.add(b2);

    add(p1);
    add(p2);

    setSize(350,125);
    addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent we)
      {
        System.exit(0);
      }
    });
  }

  class B1 implements ActionListener
  {
    public void actionPerformed(ActionEvent ae)
    {
      try
      {
        //Button ok = (Button)ae.getSource();
        //String s = ok.getLabel();
        if(ae.getSource() == b1 || ae.getSource() == b2)
        {
      System.out.println("Button Clicked");
      dispose();
      System.exit(0);
        }
      }
      catch(Exception e){} 
    }
  }
}