IBM Interview Question Developer Program Engineers


Country: India
Interview Type: Phone Interview


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A WeakHashMap is a special Map implementation where the keys of the map are stored in a java.lang.ref.WeakReference. By storing the keys in a weak reference, key-value pairs can dynamically be dropped from the map when the only reference to the key is from the weak reference. This makes the WeakHashMap an excellent implementation for a weakly referenced list, where entries that aren't used elsewhere may be dropped with no side effects. Also, just because a key may be dropped, doesn't mean it will immediately be dropped. If the system has sufficient resources, the weak key reference that isn't externally referenced could stay around for a long time.

- Satya on July 18, 2012 | Flag Reply


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