Java 7 for Absolute Beginners

CHAPTER 10 ■ ANIMATION

animationThread = new Thread(scootBallPanel);

scootBallPanel.setAnimating(true);

animationThread.start();

}

}

}

The key to the this class is the actionPerformed method. It checks for which action the user has

chosen and starts the animation if the user selects the Scoot button (and if the ball isn't already being

drawn). The animation is accomplished through the ScootBallPanel class. Because ScootBallPanel

implements the Runnable interface (meaning it can be run in its own thread), we have a means to let it

know when to start drawing the ball. Note that we create a new thread each time the Scoot button is

pressed, letting any previous thread go to garbage collection. That's a simple way to restart an animation

process.Listing 10-2 shows the ScootBallPanel class.

Listing 10-2. The ScootBallPanel class

package com.bryantcs.examples.animation;

import java.awt.Color;

import java.awt.Graphics;

import javax.swing.JPanel;

public class ScootBallPanel extends JPanel implements Runnable {

private static final long serialVersionUID = 1L;

private boolean animating = false;

private int xPosition = 5;

public boolean isAnimating() {

return animating;

}

public void setAnimating(boolean animating) {

this.animating = animating;

}

public void reset() {

xPosition = 5;

}

public void paint (Graphics g) {

int width = this.getSize().width;

int height = this.getSize().height;

super.paintComponent(g);