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

/*
 * MyDialog.java is a simple Java application to demo display
 * of a dialog box.
 */
public class MyDialog extends JPanel implements ActionListener{
    JFrame nsFrame;

    /** Creates the GUI shown inside the frame's content pane. */
    public MyDialog(JFrame frame) {
        JButton DBut = new JButton ("Pop up a dialog box!");
        DBut.setActionCommand("DB");
        DBut.addActionListener(this);
        nsFrame=frame;
        add(DBut);

    }

    public void actionPerformed(ActionEvent e) {
        if ("DB".equals(e.getActionCommand()))                
           //ok dialog               
           JOptionPane.showMessageDialog(nsFrame,
                                "Some approriate message.");
    }


    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("MyDialog");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        MyDialog newContentPane = new MyDialog(frame);
        newContentPane.setOpaque(true); //content panes must be opaque
        newContentPane.setBorder(
              BorderFactory.createEmptyBorder(20,30,20,30)); //T,L,B,R
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

}