pinballtarget.java

一些JAVA的小程序

//
//	PinBallTarget class
//
//	From Chapter 7 of
//	Understanging Object-Oriented Programming with Java
//	Written by Tim Budd
//	Published by Addison-Wesley Longman
//
//	See ftp://ftp.cs.orst.edu/pub/budd/java/ReadMe.html 
//	for further information
//
//
//	Note, in making the pinballgame 2, 
//	the static variable PinBallGame must be changed to 
//	PinBallGame2.

import java.awt.*;

interface PinBallTarget {
	public boolean intersects (Ball aBall);
	public void moveTo (int x, int y);
	public void paint (Graphics g);
	public void hitBy (Ball aBall);
}

class Spring implements PinBallTarget {
	private Rectangle pad;
	private int state;
	
	public Spring (int x, int y) {
		pad = new Rectangle(x, y, 30, 3);
		state = 1;
	}
	
	public void moveTo (int x, int y)
		{ pad.setLocation(x, y); }

	public void paint (Graphics g) {
		int x = pad.x;
		int y = pad.y;
		g.setColor(Color.black);
		if (state == 1) {
			g.fillRect(x, y, pad.width, pad.height);
			g.drawLine(x, y+3, x+30, y+5);
			g.drawLine(x+30, y+5, x, y+7);
			g.drawLine(x, y+7, x+30, y+9);
			g.drawLine(x+30, y+9, x, y+11);
			}
		else {
			g.fillRect(x, y-8, pad.width, pad.height);
			g.drawLine(x, y+5, x+30, y-1);
			g.drawLine(x+30, y-1, x, y+3);
			g.drawLine(x, y+3, x+30, y+7);
			g.drawLine(x+30, y+7, x, y+11);
			state = 1;
		}
	}
	
	public boolean intersects (Ball aBall)
		{ return pad.intersects(aBall.location); }
	
	public void hitBy (Ball aBall) {
			// make sure we are moving up
		if (aBall.dy > 0)
			aBall.dy = - aBall.dy;
			// give the ball a little boost
		aBall.dy = aBall.dy - 0.5;
		state = 2;
	}
}

class Wall implements PinBallTarget {
	public Rectangle location;
	
	public Wall (int x, int y, int width, int height)
		{ location = new Rectangle(x, y, width, height); }
	
	public void moveTo (int x, int y)
		{ location.setLocation (x, y); }

	public void paint (Graphics g) {
		g.setColor(Color.black);
		g.fillRect(location.x, location.y, location.width, location.height); 
	}
		
	public boolean intersects (Ball aBall)
		{ return location.intersects(aBall.location); }
	
	public void hitBy (Ball aBall) {
		if ((aBall.y() < location.y) || (aBall.y() > (location.y + location.height)))
			aBall.dy = - aBall.dy;
		else
			aBall.dx = - aBall.dx;
	}
}

class Hole extends Ball implements PinBallTarget {

	public Hole (int x, int y) {
		super (x, y, 12);
		setColor (Color.black);
	}
	
	public boolean intersects (Ball aBall)
		{ return location.intersects(aBall.location); }
		
	public void hitBy (Ball aBall) {
			// move ball totally off frame
		aBall.moveTo (0, PinBallGame.FrameHeight + 30);
			// stop motion
		aBall.setMotion(0, 0);
	}
}

class ScorePad extends Hole {
	protected int value;
	
	public ScorePad (int x, int y, int v) {
		super (x, y);
		value = v;
		setColor (Color.red);
	}
		
	public void hitBy (Ball aBall) { PinBallGame.world.addScore(value); }
	
	public void paint (Graphics g) {
		g.setColor (color);
		g.drawOval (location.x, location.y, location.width, location.height);
		String s = "" + value;
		g.drawString(s, location.x, y()+2);
	}
}

class Peg extends ScorePad {
	private int state = 1;
	
	public Peg (int x, int y, int v) {
		super(x, y, v);
		setColor (Color.green);
	}

	public void paint (Graphics g) {
		if (state == 2) {
			setColor (Color.red);
			g.drawOval(location.x-3, location.y-3, location.width+6, location.height+6);
			state = 1;
			}
		else {
			setColor (Color.green);
			g.drawOval(location.x-2, location.y-2, location.width+4, location.height+4);
			}
		super.paint(g);
	}
	
	public void hitBy (Ball aBall) {
		super.hitBy(aBall);
		aBall.setMotion(-aBall.dy, -aBall.dx);
		while (intersects(aBall))
			aBall.move();
		state = 2; // next draw will expand circle
	}
}