Why does exist WeakHashMap, but absent WeakSet?

Question

From J. Bloch

A ... source of memory leaks is listeners ... The best way to ensure that callbacks are garbage collected promptly is to store o

Answer 1

While you can indeed use Collections.newSetFromMap() to get a WeakSet, it's use cases are actually quite limited.

If you want to implement something like String.intern() you might want to have a look at Guava's Interners.newWeakInterner() functionality instead.