ConcurrentModificationException with WeakHashMap

Question

I have the code below but I'm getting ConcurrentModificationException, how should I avoid this issue? (I have to use WeakHashMap for some reason)

WeakHashMap<String, Object> data = new WeakHashMap<String, Object>();

 // some initialization code for data

  for (String key : data.keySet()) {
        if (data.get(key) != null && data.get(key).equals(value)) {
            //do something to modify the key
        } 
    }

Answer 1

Probably because your // do something in the iteration is actually modifying the underlying collection.

From ConcurrentModificationException:

For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception.

And from (Weak)HashMap's keySet():

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined.