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POConcurrentModificationException when removing bullet from game
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  1. POConcurrentModificationException when removing bullet from game
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    copied!<p>I have to create Space Invaders for my programming course in college which would be fine but I have a problem with removing a bullet from the game.</p> <p>I'm storing all my enemies and bullets in separate ArrayLists.</p> <p>This is my main class.</p> <pre><code>package uk.ac.wnc.pot13000765.space_invaders; import java.util.ArrayList; import org.lwjgl.LWJGLException; import org.lwjgl.opengl.Display; import org.lwjgl.opengl.DisplayMode; import org.lwjgl.opengl.GL11; public class SpaceInvaders { private ArrayList&lt;Enemy&gt; enemies = new ArrayList&lt;Enemy&gt;(); private static ArrayList&lt;Bullet&gt; bullets = new ArrayList&lt;Bullet&gt;(); private Player player; public SpaceInvaders() { //Setup and create the OpenGL Context + Window try { Display.setDisplayMode(new DisplayMode(800, 600)); Display.setTitle("Unit 14 Space Invaders in Java by Liam Potter - POT13000765"); Display.create(); GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); GL11.glOrtho(0, 800, 0, 600, 1, -1); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glClearColor(0f, 0f, 0f, 1f); GL11.glEnable(GL11.GL_BLEND); GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA); } catch(LWJGLException e) { System.err.print(e); System.exit(1); } Time.getDelta(); Time.setLastFps(Time.getTime()); //Setup player = new Player(40, 40, 50, 50); //Enemies enemies.add(new Enemy(40, 540, 25, 25)); while(!Display.isCloseRequested()) { gameLoop(Time.getDelta()); } Display.destroy(); } private void gameLoop(int delta) { GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); //Update player.update(delta); if(enemies.size() &gt; 0) for(Enemy e: enemies) e.update(delta); if(bullets.size() &gt; 0) for(Bullet b: bullets) b.update(delta); //Render player.draw(); if(enemies.size() &gt; 0) for(Enemy e: enemies) e.draw(); if(bullets.size() &gt; 0) for(Bullet b: bullets) b.draw(); Display.sync(60); Display.update(); Time.updateFps(); } public int getWindowWidth() { return Display.getWidth(); } public int getWindowHeight() { return Display.getHeight(); } public static void spawnBullet(Bullet b) { bullets.add(b); } public static void destroyBullet(Bullet b) { bullets.remove(b); } public static void main(String[] args) { new SpaceInvaders(); } } </code></pre> <p>And this is my Bullet class:</p> <pre><code>package uk.ac.wnc.pot13000765.space_invaders; import org.lwjgl.opengl.GL11; public class Bullet extends Entity { public Bullet(int x, int y, int width, int height) { super(x, y, width, height); } @Override public void update(int delta) { if(!(getY() &gt; 600)) setY(getY() + 1); else dispose(); System.out.println(getY()); } @Override public void draw() { GL11.glColor3f(1.0f, 0.5f, 0.5f); GL11.glBegin(GL11.GL_QUADS); GL11.glVertex2i(getX(), getY()); GL11.glVertex2i(getX() + getWidth(), getY()); GL11.glVertex2i(getX() + getWidth(), getY() + getHeight()); GL11.glVertex2i(getX(), getY() + getHeight()); GL11.glEnd(); } @Override public void dispose() { SpaceInvaders.destroyBullet(this); } } </code></pre> <p>This is the exact error I am getting:</p> <pre><code>Exception in thread "main" java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(Unknown Source) at java.util.ArrayList$Itr.next(Unknown Source) at uk.ac.wnc.pot13000765.space_invaders.SpaceInvaders.gameLoop(SpaceInvaders.java:62) at uk.ac.wnc.pot13000765.space_invaders.SpaceInvaders.&lt;init&gt;(SpaceInvaders.java:50) at uk.ac.wnc.pot13000765.space_invaders.SpaceInvaders.main(SpaceInvaders.java:91) </code></pre> <p>I understand that I can use ListIterators to fix this but I can't figure out how to implement them in my main class.</p>
 

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