1. Animating with EventTimer
Lecture 8.5
Animating with EventTimer

2. A Crash Course in the Use of Timed Events
What kinds of occurrences produce events?
How does the event handling mechanism work?
© 2006 Pearson Addison-Wesley. All rights reserved

3. EventTimer for building computer “alarm clocks”
javax.swing.Timer
EventTimer
«constructor»
+ EventTimer(int)
«update»
+ start()
+ stop()
«event handler»
+ void actionPerformed( java.awt.event.ActionEvent )
time between consecutive events (in milliseconds)
© 2006 Pearson Addison-Wesley. All rights reserved

4. public class Clock extends EventTimer {
import java.awt.event.*;
public class Clock extends EventTimer {
private Driver theDriver;
/** post: theDriver == d */
public Clock( Driver d, int t ) {
super( t );
theDriver = d; }
public void actionPerformed( ActionEvent e ) {
theDriver.clockHasTicked();
import javax.swing.JFrame;
public class Driver {
private Clock animator;
private Oval dot;
private JFrame win;
public Driver() {
win = new JFrame();
win.setBounds(0,0,200,200);
win.setLayout(null);
win.setVisible(true);
dot = new Oval(0, 0, 30, 30);
win.add(dot, 0);
win.repaint();
animator = new Clock(this, 50);
animator.start(); }
public void clockHasTicked() {
if (dot.getX() > 195)
dot.setLocation(0, 0);
else
dot.setLocation(dot.getX()+1, 0);
dot.repaint();
© 2006 Pearson Addison-Wesley. All rights reserved