How to fix ConcurrentModificationException in this code?

Question

I'm trying to fix this problem, but in any case I do does not fix. Could someone help me?

for(Iterator<Block> iterator = event.blockList().iterator(); iterator.hasNext();)
{
    Block b = iterator.next();

    if (((RegiaoCuboid) r).contains(b))
        event.blockList().remove(b);
}

Please research before posting to SO. This exact question with the same problem has been asked and answered many, many times on SO. — djechlin, Apr 14 '13 at 22:41
How did you search? Did you google "java fix concurrentmodificationexception" and read the results? — djechlin, Apr 14 '13 at 22:50

Reimeus · Accepted Answer · 2013-04-14T22:57:57.897

3

Remove using the iterator:

iterator.remove();

A ConcurrentModificationException is thrown when a collection changes in a manner which invalidates open iterators. In this case you are calling remove directly on the collection.

edited Apr 14 '13 at 22:57

answered Apr 14 '13 at 22:40

Reimeus

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Thanks, I had forgotten that could do that. – Lucas Fernando Apr 14 '13 at 22:48

score -2 · Answer 2 · answered Apr 14 '13 at 22:42

-2

You can't modify a List while iterating over it. I would suggest adding the Blocks you wish to remove to a new List, then iterating over that and removing them from the main one (EDIT: Or, do what the other person said). Additionally, if you're doing what I think you are, I would suggest asking further questions on the Bukkit Forums. This question is more general, but Bukkit-specific questions will be more easily answered by individuals who are familiar with the area.

answered Apr 14 '13 at 22:42

Max Roncace

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False, see other answer. – djechlin Apr 14 '13 at 22:43
Not true, as @Reimeus correctly points out `Iterator` has a remove method. – Boris the Spider Apr 14 '13 at 22:43

How to fix ConcurrentModificationException in this code?

2 Answers2