如何在任何Java映射实现上测试空键？ [英] How to test for null keys on any Java map implementation?

问题描述

我想确保作为参数传递给方法的Map不包含空键。人们会假设以下情况会做到：

I would like to ensure that a Map being passed as an argument to a method doesn't include null keys. One would assume that the following would do:

if ( map.containsKey(null) ) …

，但是如果方法通过类似 TreeMap 这样的方法，则会中断每个常规Java Map合同的可以自由地使用NPE拒绝空键。

but that will break if the method is passed something like a TreeMap, which per the general Java Map contract is free to reject null keys with a NPE.

在接受任何Map实现的同时，我们是否有一种明智的方法来测试空键？

Do we have a sensible way to test for null keys while accepting any Map implementation?

推荐答案

boolean hasAnyNull = yourMap.keySet()
      .stream()
      .anyMatch(Objects::isNull);

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