Comment by j on "How to get the overridden values from map ??"

That's not entirely true, it's very easy to see if there was a collision in the map.

Map.put has a return value that is often ignored but it is useful in exactly this situation.

@return the previous value associated with <tt>key</tt>, or

<tt>null</tt> if there was no mapping for <tt>key</tt>.

(A <tt>null</tt> return can also indicate that the map

previously associated <tt>null</tt> with <tt>key</tt>,

if the implementation supports <tt>null</tt> values.)

So to detect a collision all you have to do is see if map.put returns a non null value. You can then do something with the previous value if you want. You could also just check to see if the map contains a value before you put to detect it yourself.

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