迭代并从地图中删除 [英] iterating over and removing from a map

问题描述

我在做:

for (Object key : map.keySet())
    if (something)
        map.remove(key);

抛出了 ConcurrentModificationException，所以我将其更改为:

which threw a ConcurrentModificationException, so i changed it to:

for (Object key : new ArrayList<Object>(map.keySet()))
    if (something)
        map.remove(key);

这个和任何其他修改映射的过程都在同步块中.

this, and any other procedures that modify the map are in synchronized blocks.

有更好的解决方案吗?

推荐答案

从 Java 8 开始，您可以按如下方式执行此操作:

As of Java 8 you could do this as follows:

map.entrySet().removeIf(e -> <boolean expression>);

Oracle 文档:entrySet()

Oracle Docs: entrySet()

集合由地图支持，因此对地图的更改会反映在集合中，反之亦然

The set is backed by the map, so changes to the map are reflected in the set, and vice-versa

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