All collection collections can have null items. Including sets (but only one allowed). This means others can have more than one. Maps can have one key as null, and multiple values as null. I am little bit doubtful. Can anyone confirm me please? thanks, Natarajan
Set can have no dups and at most 1 null. List can have dups and many nulls. Maps can have no dup keys (but can have dup elements) and SOME maps allow nulls HashMap allows nulls TreeMap allow nulls EXCEPT those that use natural ordering. HashTable does NOT allow nulls.
"JavaRanch, where the deer and the Certified play" - David O'Meara