public class JDialog extends Dialog implements WindowConstants, Accessible, RootPaneContainer

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class DialogExample {
private static JDialog d;
DialogExample() {
JFrame f= new JFrame();
d = new JDialog(f , "Dialog Example", true);
d.setLayout( new FlowLayout() );
JButton b = new JButton ("OK");
b.addActionListener ( new ActionListener()
{
public void actionPerformed( ActionEvent e )
{
DialogExample.d.setVisible(false);
}
});
d.add( new JLabel ("Click button to continue."));
d.add(b); 
d.setSize(300,300);  
d.setVisible(true);
}
public static void main(String args[])
{
new DialogExample();
}
}