colorfulballmover.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;
import java.awt.*;
import java.applet.*;

// Animator for a BallList, changes colors while moving
public class ColorfulBallMover extends ActiveObject {

    private static final int PAUSETIME = 20;
    private static final double SPEED = 1;
    
    private AudioClip noise;
    
    // the list of balls to animate
    private BallListInterface ballList;
    
    // distance that each ball should move
    private int distanceToMove;
    
    public ColorfulBallMover(BallListInterface aList, int distance, AudioClip theNoise) {
        ballList = aList;
        distanceToMove = distance;
        noise = theNoise;
        
        start();
    }
   
    // move the specified ball
    private void moveOneBall(FilledOval ball) {
        double pixelsMoved = 0;
        while (pixelsMoved < distanceToMove) {
            ball.move(SPEED, 0);
            pause(PAUSETIME);
            pixelsMoved = pixelsMoved + SPEED;
        }
    }
    
    // traverse the list, move each ball once, and change its color
    public void run() {
        RandomIntGenerator gen = new RandomIntGenerator(0, 255);
        while (!ballList.isEmpty()) {
            FilledOval nextBall = ballList.getFirst();
            Color c = new Color(gen.nextValue(), gen.nextValue(), gen.nextValue());
            nextBall.setColor(c);
            noise.play();
            moveOneBall(nextBall);
            ballList = ballList.getRest();
        }
    }
}