Question

Is there a simple way of removing null references from a HashSet like
the way we can delete them from a List using list.removeAll(Collections.singletonList(null)) ?

Answer 1

Since a Set can not contain the same value twice (including null, if it is supported by the specific Set implementation), simply doing set.remove(null) would be sufficient.

Note that you don’t even need to check for the existence of null before, because remove(null) will simply do nothing if the Set doesn’t contain null.