为什么存在 WeakHashMap，而没有 WeakSet? [英] Why does exist WeakHashMap, but absent WeakSet?

问题描述

来自 J.布洛赫

一个......内存泄漏的来源是听众... 确保回调是垃圾收集及时只是存储弱对它们的引用，例如，将它们仅作为密钥存储在WeakHashMap.

A ... source of memory leaks is listeners ... The best way to ensure that callbacks are garbage collected promptly is to store only weak references to them, for instance, by storing them only as keys in a WeakHashMap.

那么，为什么 Java 集合框架中没有任何 WeakSet?

So, why there isn't any WeakSet in the Java Collections framework?

推荐答案

Collections.newSetFromMap

Set<Object> weakHashSet = 
    Collections.newSetFromMap(
        new WeakHashMap<Object, Boolean>()
    );

如Collections.newSetFromMap 文档，传递一个 WeakHashMap 获取Set.

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