java - If I always return 0 in Comparator.compare() why do I end-up with 1 item in my Set? -

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i wrote custom comparator treeset. debug, decided hardwire "compare()" return 0. surprise, 1 item entered set.

why be? i'm doing best understand relationship between "set.add()" , "compare()".

always returning 0 means items equal other items.

that not prevent adding single possible item.


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