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Thread: Question : Collection

  1. #1
    Junior Member
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    Default Question : Collection

    How can allow duplicate value in set show by doing program....

  2. #2
    Super Moderator Norm's Avatar
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    May 2010
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    Default Re: Question : Collection

    A Set does not have duplicate elements.
    Can you explain what you are trying to do?
    An ArrayList can have duplicate values.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Super Moderator helloworld922's Avatar
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    Default Re: Question : Collection

    A set's definition is a collection of unique items, so it doesn't make sense to have duplicate values.

    There are things known as "multi-sets" or "multi-maps" which do allow duplicate values, but there are no standard implementations in Java.

    The simplest way to get something that appears like a multi-map is to create a map with a List for each key. See: The Java Tutorials: The Map Interface

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