Write a CompositeIterator and use it to clean up entity iteration

core/src/com/me/brickbuster/state/PlayState.java

@@ -2,17 +2,20 @@ package com.me.brickbuster.state;
 
 import com.badlogic.gdx.Gdx;
 import com.badlogic.gdx.graphics.Color;
-import com.badlogic.gdx.graphics.Texture;
-import com.badlogic.gdx.graphics.g2d.TextureRegion;
 import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.physics.box2d.*;
 import com.badlogic.gdx.utils.Array;
 import com.me.brickbuster.BrickBuster;
+import com.me.brickbuster.utils.CompositeIterator;
 import com.me.brickbuster.entity.*;
 import com.me.brickbuster.entity.powerup.PowerUp;
-import com.me.brickbuster.layout.*;
+import com.me.brickbuster.layout.BrickLayout;
+import com.me.brickbuster.layout.FileLevelLoader;
+import com.me.brickbuster.layout.Level;
+import com.me.brickbuster.layout.LevelLoader;
 import com.me.brickbuster.physics.Box2dContactListener;
 import com.me.brickbuster.physics.EntityType;
+import com.me.brickbuster.physics.PhysicsBody;
 
 import java.util.Iterator;
 
@@ -81,25 +84,20 @@ public class PlayState extends FieldState {
 		long start = System.nanoTime();
 
 		game.sb.begin();
-		for (Brick block : bricks) {
-			block.render(game.sb, game.sr);
-		}
-		for (Ball ball : balls) {
-			ball.render(game.sb, game.sr);
+		Iterator<? extends Entity> it = CompositeIterator.concat(balls, bricks);
+		while (it.hasNext()) {
+			it.next().render(game.sb, game.sr);
 		}
 		game.sb.end();
 
-		for (PowerUp powerUp : powerUps) {
-			powerUp.render(game.sb, game.sr);
-		}
-		for (Shield shield : shields) {
-			shield.render(game.sb, game.sr);
+		it = CompositeIterator.concat(powerUps, shields);
+		while (it.hasNext()) {
+			it.next().render(game.sb, game.sr);
 		}
 		paddle.render(game.sb, game.sr);
 
 		//debugRenderer.render(world, game.cam.combined.cpy().scl(PIXEL_PER_METER));
 		long renderTime = System.nanoTime() - start;
-
 		game.fb.begin();
 		game.font.setColor(Color.GRAY);
 		game.font.draw(game.fb, String.format("FPS: %d Update: %.2f ms Render: %.2f ms",
@@ -110,47 +108,26 @@ public class PlayState extends FieldState {
 	@Override
 	public void update(float dt) {
 		long start = System.nanoTime();
+
 		paddle.update(dt);
 
-		for (Iterator<Ball> it = balls.iterator(); it.hasNext();) {
-			Ball ball = it.next();
-			ball.update(dt);
-			if (ball.isDeleted()) {
+		Iterator<? extends Entity> it = CompositeIterator.concat(balls, powerUps, shields, bricks);
+		while (it.hasNext()) {
+			Entity ent = it.next();
+			ent.update(dt);
+			if (ent.isDeleted()) {
 				it.remove();
-				world.destroyBody(ball.getBody());
+				if (ent instanceof PhysicsBody) {
+					world.destroyBody(((PhysicsBody) ent).getBody());
+				}
+				ent.dispose();
 			}
 		}
+
 		if (balls.size == 0) {
 			ballReset();
 		}
 
-		for (Iterator<PowerUp> it = powerUps.iterator(); it.hasNext();) {
-			PowerUp powerUp = it.next();
-			powerUp.update(dt);
-			if(powerUp.isDeleted()) {
-				it.remove();
-				world.destroyBody(powerUp.getBody());
-			}
-		}
-
-		for (Iterator<Shield> it = shields.iterator(); it.hasNext();) {
-			Shield shield = it.next();
-			shield.update(dt);
-			if(shield.isDeleted()) {
-				it.remove();
-				world.destroyBody(shield.getBody());
-			}
-		}
-
-		for (Iterator<Brick> it = bricks.iterator(); it.hasNext();) {
-			Brick brick = it.next();
-			brick.update(dt);
-			if (brick.isDeleted()) {
-				it.remove();
-				brick.dispose();
-				world.destroyBody(brick.getBody());
-			}
-		}
 		if (bricks.size == 0) {
 			currentLevel = levelLoader.getNextLevel();
 			if (currentLevel == null) {
@@ -161,7 +138,6 @@ public class PlayState extends FieldState {
 			}
 			return;
 		}
-
 		world.step(dt, 6, 2);
 		updateTime = System.nanoTime() - start;
 	}

core/src/com/me/brickbuster/utils/CompositeIterator.java

@@ -0,0 +1,43 @@
+package com.me.brickbuster.utils;
+
+import java.util.Iterator;
+
+public class CompositeIterator<T> implements Iterator<T> {
+
+	private short index = 0;
+	private Iterator<? extends T> iterator;
+	private Iterable<? extends T>[] iterables;
+
+	private CompositeIterator(Iterable<? extends T>... iterables) {
+		this.iterables = iterables;
+		this.iterator = iterables[index].iterator();
+	}
+
+	@Override
+	public boolean hasNext() {
+		if (iterator.hasNext()) {
+			return true;
+		} else {
+			if (++index < iterables.length) {
+				iterator = iterables[index].iterator();
+				return hasNext();
+			}
+		}
+		return false;
+	}
+
+	@Override
+	public T next() {
+		return iterator.next();
+	}
+
+	@Override
+	public void remove() {
+		iterator.remove();
+	}
+
+	public static <E> CompositeIterator<E> concat(Iterable<? extends E>... iterables) {
+		return new CompositeIterator<E>(iterables);
+	}
+
+}