ConcurrentModificationException Woes [duplicate]

Answer 1

You could use an iterator:

for (Iterator<Entry<String, BigDecimal>> it = testBene.entrySet().iterator(); it.hasNext();) {
    Entry<String, BigDecimal> beneKeySet = it.next();
    if (testDly.containsKey(beneKeySet.getKey())) {
        for (Entry<String, BigDecimal> dlyKeySet : testDly.entrySet()) {
            if ((dlyKeySet.getKey() == beneKeySet.getKey()) && dlyKeySet.getValue() == beneKeySet.getValue()) {
                it.remove();
            }
        }
    }
}

Answer 2

You cannot remove from a list you're currently iterating with a for each. Use the list's iterator to do this.

Answer 3

Instead of removing the elements, put the keys that you want to remove into a separate collection. At the end, traverse that other collection, removing the keys from your map.

Alternatively, use the Iterator interface instead of the for-each loop. This will enable you to use Iterator.remove() to remove elements while iterating.

Answer 4

You can use EntrySet's iterator, or save all duplicated keys in another list, and later remove those from the map. Also, do not compare objects using ==, use the equals() function.