ballworld.java

一些JAVA的小程序

//
//	the Ball World game
//	Described in Chapter 5 of
//	Understanding Object-Oriented Programming with Java
//	by Timothy A Budd
//	Published by Addison-Wesley
//
//	see ftp://ftp.cs.orst.edu/pub/budd/java/ReadMe.html
//	for further information
//

import java.awt.*;


public class BallWorld extends Frame {

	public static void main (String [ ] args)
	{
		BallWorld world = new BallWorld (Color.red);
		world.show ();
	}

	private static final int FrameWidth = 600;
	private static final int FrameHeight = 400;
	private Ball aBall;
	private int counter = 0;

	private BallWorld (Color ballColor) {
		// constructor for new ball world
			// resize our frame
		setSize (FrameWidth, FrameHeight);
		setTitle ("Ball World");

			// initialize object data field
		aBall = new Ball (10, 15, 5);
		aBall.setColor (ballColor);
		aBall.setMotion (3.0, 6.0);
	}

	public void paint (Graphics g) {
			// first, draw the ball
		aBall.paint (g);
			// then move it slightly
		aBall.move();
		if ((aBall.x() < 0) || (aBall.x() > FrameWidth))
			aBall.setMotion (-aBall.xMotion(), aBall.yMotion());
		if ((aBall.y() < 0) || (aBall.y() > FrameHeight))
			aBall.setMotion (aBall.xMotion(), -aBall.yMotion());
				// finally, redraw the frame
		counter = counter + 1;
		if (counter < 2000) repaint();
		else System.exit(0);
	}
}