weakhashmap

Using WeakHashMap solves the problem of Thread objects not getting garbage collected , at some additional performance cost .

以一些额外的性能开销为代价，使用WeakHashMap解决了无法对Thread对象进行垃圾回收的问题。

The implementation of WeakHashMap illustrates a common idiom with weak references & that some internal object extends WeakReference .

WeakHashMap的实现展示了弱引用的一种常见用法&一些内部对象扩展WeakReference。

When you add a mapping to a WeakHashMap , remember that it is possible that the mapping could " fall out " later because the key is garbage collected .

在向WeakHashMap中添加映射时，请记住映射可能会在以后“脱离”，因为键被垃圾收集了。

WeakHashMap has a private method called expungeStaleEntries () that is called during most Map operations , which polls the reference queue for any expired references and removes the associated mappings .

WeakHashMap有一个名为expungeStaleEntries（）的私有方法，大多数Map操作中会调用它，它去掉引用队列中所有失效的引用，并删除关联的映射。

Because this is such a common use for weak references , WeakHashMap , which uses weak references for keys ( but not for values ), was also added to the class library in JDK1.2 .

因为这是弱引用最常见的用法，WeakHashMap也被添加到JDK1.2的类库中，它对键（而不是对值）使用弱引用。