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

public class DialogEarthquakeCenter extends Object {

    public static final int SHAKE_DISTANCE = 10;
    public static final double SHAKE_CYCLE = 50;
    public static final int SHAKE_DURATION = 1000;
    public static final int SHAKE_UPDATE = 5;

    private JDialog dialog;
    private Point naturalLocation;
    private long startTime;
    private Timer shakeTimer;
    private final double HALF_PI = Math.PI / 2.0;
    private final double TWO_PI = Math.PI * 2.0;

    public DialogEarthquakeCenter (JDialog d) {
        dialog = d;
    }

    public void startShake() {
        naturalLocation = dialog.getLocation();
        startTime = System.currentTimeMillis();
        shakeTimer =
            new Timer(SHAKE_UPDATE,
                      new ActionListener() {
                          public void actionPerformed (ActionEvent e) {
                              // calculate elapsed time
                              long elapsed = System.currentTimeMillis() -
                                  startTime;
                              // use sin to calculate an x-offset
                              double waveOffset = (elapsed % SHAKE_CYCLE) /
                                  SHAKE_CYCLE;
                              double angle = waveOffset * TWO_PI;

                              // offset the x-location by an amount 
                              // proportional to the sine, up to
                              // shake_distance
                              int shakenX = (int) ((Math.sin (angle) *
                                                    SHAKE_DISTANCE) +
                                                   naturalLocation.x);
                              dialog.setLocation (shakenX, naturalLocation.y);
                              dialog.repaint();

                              // should we stop timer?
                              if (elapsed >= SHAKE_DURATION)
                                  stopShake();
                          }
                      }
                      );
        shakeTimer.start();
    }

    public void stopShake() {
        shakeTimer.stop();
        dialog.setLocation (naturalLocation);
        dialog.repaint();
    }


public static void main (String[] args) {
    JOptionPane pane =
        new JOptionPane ("You've totally screwed up your login\n" +
                         "Go back and do it again... and do you think\n"  +
                         "you could remember your password this time?",
                         JOptionPane.ERROR_MESSAGE,
                         JOptionPane.OK_OPTION);
    JDialog d = pane.createDialog (null, "Shakin'!");
    DialogEarthquakeCenter dec = new DialogEarthquakeCenter (d);
    d.pack();
    d.setModal (false);
    d.setVisible(true);
    dec.startShake();

    // wait (forever) for a non-null click and then quit
    while (pane.getValue() == JOptionPane.UNINITIALIZED_VALUE ) {
        try { Thread.sleep(100); }
        catch (InterruptedException ie) {}
    }
    System.exit(0);
}

}