Removing null references from a HashSet

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)) ?

score 62 · Accepted Answer · answered Sep 19 '11 at 08:57

62

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.

answered Sep 19 '11 at 08:57

Joachim Sauer

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Is there a .NET alternative to a `HashSet` that does not allow null values? – Shimmy Weitzhandler Mar 27 '20 at 03:10

score 4 · Answer 2 · answered Sep 19 '11 at 08:58

4

A HashSet, being a set, only contains one "copy" of any object, which also means that it can only contain one instance of null. Thus, you can just use HashSet.remove(null).

answered Sep 19 '11 at 08:58

Tikhon Jelvis

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Removing null references from a HashSet

2 Answers2