java 从 HashSet 中删除空引用
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Removing null references from a HashSet
提问by Mouna Cheikhna
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))?
有没有一种简单的方法可以从 HashSet 中删除空引用，就像我们可以使用从 List 中删除它们的方式一样list.removeAll(Collections.singletonList(null))？
回答by Joachim Sauer
Since a Setcan not contain the same value twice (including null, if it is supported by the specific Setimplementation), simply doing set.remove(null)would be sufficient.
由于 aSet不能包含两次相同的值（包括null，如果特定Set实现支持），只需执行即可set.remove(null)。
Note that you don't even need to check for the existence of nullbefore, because remove(null)will simply do nothing if the Setdoesn't contain null.
请注意，您甚至不需要检查nullbefore的存在，因为remove(null)如果Set不包含null.
回答by Tikhon Jelvis
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).
AHashSet作为一个集合，只包含任何对象的一个“副本”，这也意味着它只能包含 的一个实例null。因此，您可以只使用HashSet.remove(null).
