How to select duplicate values from a list in java?

Question

For example my list contains {4, 6, 6, 7, 7, 8} and I want final result = {6, 6, 7, 7}

One way is to loop through the list and eliminate unique values (4, 8 in this

Answer 1

The following will work with Eclipse Collections:

IntBag bag = IntLists.mutable.with(4, 6, 6, 7, 7, 8).toBag().selectDuplicates();

If you want boxed values instead of primitives, the following will work:

Bag bag = Lists.mutable.with(4, 6, 6, 7, 7, 8).toBag().selectDuplicates();

Note: I am a committer for Eclipse Collections.