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Message:

Collections framework: How to do a bag union?

Posted by Steven Tolkin on April 24, 2000 at 5:44 PM

Suppose collection b1 is [a, a, b] and collection b2 is [a, c].
Using addAll it is easy to compute "additive union", which is
[a, a, a, b, c]. But how can I compute the "bag union" (which C++ STL
calls set_union), i.e. [a, a, b, c]. In a bag union
the result contains as many instances of each element as
were in the input having the greater number.