Refactor to support multiple balls

core/src/com/me/brickbuster/BrickBuster.java

@@ -27,20 +27,20 @@ public class BrickBuster extends ApplicationAdapter {
 	private BitmapFont font;
 	private SpriteBatch batch;
 
-	private Ball ball;
 	private Paddle paddle;
+	private ArrayList<Ball> balls;
 	private ArrayList<Brick> bricks;
 	private ArrayList<PowerUp> powerUps;
-	private boolean playing = false;
 
 	@Override
 	public void create () {
 		font = new BitmapFont();
 		batch = new SpriteBatch();
 
-		ball = new Ball(this);
 		paddle = new Paddle(this);
+
 		powerUps = new ArrayList<PowerUp>();
+
 		bricks = new ArrayList<Brick>();
 		for (int col = 0; col < 13; col++) {
 			for (int row = 0; row < 7; row++) {
@@ -56,6 +56,9 @@ public class BrickBuster extends ApplicationAdapter {
 				bricks.add(new Brick(this, powerUpType, x, HEIGHT - y));
 			}
 		}
+
+		balls = new ArrayList<Ball>();
+		balls.add(new Ball(this));
 	}
 
 	@Override
@@ -74,7 +77,9 @@ public class BrickBuster extends ApplicationAdapter {
 		for (PowerUp powerUp : powerUps) {
 			powerUp.render();
 		}
-		ball.render();
+		for (Ball ball : balls) {
+			ball.render();
+		}
 		paddle.render();
 		long finish_render = System.nanoTime() - start_render;
 
@@ -86,13 +91,19 @@ public class BrickBuster extends ApplicationAdapter {
 	}
 
 	public void update(float dt) {
-		if (Gdx.input.justTouched() && (!isPlaying() || ball.isStuck())) {
-			playing = true;
-			ball.launch();
+		for (Iterator<Ball> it = balls.iterator(); it.hasNext();) {
+			Ball ball = it.next();
+			ball.update(dt);
+			if (ball.isDead()) {
+				it.remove();
+			}
 		}
-		ball.update(dt);
-		paddle.update(dt);
 
+		if (balls.isEmpty()) {
+			reset();
+		}
+
+		paddle.update(dt);
 
 		for (Iterator<PowerUp> it = powerUps.iterator(); it.hasNext();) {
 			PowerUp powerUp = it.next();
@@ -104,24 +115,25 @@ public class BrickBuster extends ApplicationAdapter {
 
 		if (getBricks().isEmpty()) {
 			create();
-			playing = false;
 		}
 	}
 
+	public void reset() {
+		Paddle paddle = getPaddle();
+		Ball ball = new Ball(this);
+		ball.setX(paddle.getX());
+		ball.setY(Paddle.PADDLE_Y + Paddle.PADDLE_HEIGHT + Ball.RADIUS);
+		balls.add(ball);
+		paddle.setSticky(false);
+		paddle.setWidth(Paddle.DEFAULT_WIDTH);
+	}
+
 	@Override
 	public void dispose () {
 	}
 
-	public boolean isPlaying() {
-		return playing;
-	}
-
-	public void setPlaying(boolean playing) {
-		this.playing = playing;
-	}
-
-	public Ball getBall() {
-		return ball;
+	public ArrayList<Ball> getBalls() {
+		return balls;
 	}
 
 	public Paddle getPaddle() {
@@ -136,4 +148,4 @@ public class BrickBuster extends ApplicationAdapter {
 		this.powerUps.add(powerUp);
 	}
 
-}
+}