Hello! An exception appears in this piece of code . moreover, after the 1st method call from return. It seems that the collection gets a new iterator and works with it, but something goes wrong.

Closed due to the fact that off-topic participants fori1ton , Alexey Shimansky , Kromster , ermak0ff , user194374 16 Feb '17 at 5:58 .

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    Possible duplicate issue: ConcurrentModificationException - Alexey Shimansky

1 answer 1

You remove or modify items by iterating through the collection. Use an alternate pass method instead of an iterator (for example, a simple loop other than for each ).

You cannot use Iterator and, at the same time, add or remove items from the collection. ConcurrentModificationException is the same and says that you are simultaneously modifying the collection.

A similar error will occur if you use the for each loop, changing the elements in it. For this, either do while is suitable, or simple for .

  • Yes, thanks, redid. But where was the removal? With waves = tempWaves? But after all, the iterator was always new - Oleg Rosaybeda
  • @OlegRozibeda, I apologize, did not fully write. Adding, by meaning, leads to a similar result. I came across only deletion, so I wrote about it :). - Rostislav Dugin
  • Yes, I know that, but where was the addition? I'm adding all the new objects to a completely different collection, not the one from which I got an iterator - Oleg Rozdaybeda
  • @ OlegRazdaybeda, in this piece of code - I do not see. But outside of the method, it is modified somewhere. Search for matches by iter. . - Rostislav Dugin
  • no, outside of this piece of code, iter is no longer used - Oleg Rozdaybeda