BallArray.java

/*************************************************************************
 *  Compilation:  javac BallArray.java
 *  Execution:    java BallArray N
 *  Dependencies: ColoredBall.java StdDraw.java
 *
 *  Creates an array of N balls and animates them.
 *
 *  % java BallArray 10
 *
 *  Remarks
 *  -------
 *  For some reason the compiler sometimes complains about the call
 *  to the method Ball.move. Is this a reserved name? Or compiler glitch?
 *
 *************************************************************************/

import java.awt.Color;

public class BallArray { 
    private ColoredBall[] balls;

    // initialze an an array of N balls
    BallArray(int N) {
        balls = new ColoredBall[N];
        for (int i = 0; i < N; i++)
            balls[i] = new ColoredBall();
    }

    // move all of the balls
    public void update() {
        for (int i = 0; i < balls.length; i++)
            balls[i].update();
    }

    // draw all of the balls
    public void draw() {
        for (int i = 0; i < balls.length; i++)
            balls[i].draw();
    }


   // test client
   public static void main(String[] args) {
      int N = Integer.parseInt(args[0]);      // number of bouncing balls

      int SIZE = 512;
      StdDraw.create(512, 512);
      StdDraw.setScale(-1, -1, 1, 1);


      BallArray balls = new BallArray(N);

      // the animation loop
      while(true) {
         StdDraw.clear(Color.black);
         balls.update();
         balls.draw();
         StdDraw.pause(20);
      }
   }
}