从值不是我在寻找的HashMap中删除所有条目 [英] Remove all entries from HashMap where value is NOT what I'm looking for

问题描述

标题问题很好地总结了一下，但是假设我正在用Java编写代码，并且有一个HashMap看起来像这样(显然有很多条目):

The title question summarizes it nicely, but assume I am coding in Java and have a HashMap that looks something like this (it has a lot more entries obviously):

Map<String, Integer> myMap = new HashMap<>();

myMap.put{"a", 1}
myMap.put{"b", 2}
myMap.put{"c", 2}
myMap.put{"d", 3}

现在我不喜欢值为2的条目，因此我想尽可能有效地删除它们 all ，只剩下那些具有值1或3.

Now I don't like entries with the value of 2, so I want to remove them all as effectively as possible, leaving me only with the entries that have value 1 or 3.

看起来好像我的地图是这样制作的:

It should look as if my map was instead made like this:

Map<String, Integer> myMap = new HashMap<>();

myMap.put{"a", 1}
myMap.put{"d", 3}

好像我的2值条目根本就不存在！

As if my 2-valued entries were never there at all!

以有效方式执行此操作有哪些选择?

What are my options for doing this in an effective way?

推荐答案

map.entrySet().removeIf(entry -> entry.getValue() == 2)

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