Removing object from ArrayList in Java

Question

I have this, where everytime a Bullet reaches the position greater than my screen width, it has to be destroyed. When i try this, the game crashes.

"bullet" is my class which contains the i's as objects.

"bullets" is my arraylist, containg all of the objects.

EDIT: Trying with Iterator now, but still still crashes.

EDIT: Accepted answer helped me. Working now. Thanks!

public ArrayList<bullet> bullets = new ArrayList<bullet>();
public Iterator<bullet> it = bullets.iterator();

while (it.hasNext()) {
           bullet s = it.next();
           if(s.xPosition > screenWidth - 10) {
               it.remove();
           }
        }

possible duplicate of Efficient equivalent for removing elements while iterating the Collection — Rohit Jain
– Rohit Jain, Commented Feb 11, 2013 at 13:50
What do you mean by crash? Do you have NullPointerException? Can you be more explicit about the error you have? — Dimitri
– Dimitri, Commented Feb 11, 2013 at 13:54

PermGenError · Accepted Answer · 2013-02-11 13:50:12Z

2

You cannot remove elements from your List while iterating over it. you will get ConcurrentModificationException if you do it. you should use an iterator and remove elements from the iterator.

Iterator<Bullet> itr = bullets.iterator();
while(itr.hasNext()) {
    if(itr.next().xPosition > screenWidth - 10) {
        itr.remove(i);
    }
}

answered Feb 11, 2013 at 13:50

PermGenError

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2 Comments

Kevin Jensen Petersen Over a year ago

Well, that's cool and everything, but that didn't really help me alot, since i don't know how to make one of these.

PermGenError Over a year ago

@KevinJensenPetersen check out duplicate posted as a comment under your question .

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