Here is the answer.
An object is weakly reachable when the garbage collector finds no strong or soft references but at least one path to the object with a weak reference.
A weak reference is one that does not prevent the referenced object from being garbage collected. Weakly reachable objects are finalized some time after their weak references have been cleared.
A weak reference is a reference that does not keep the object it refers to alive. A weak reference is not counted as a reference in garbage collection. If the object is not referred to elsewhere as well, it will be garbage collected.