Iterative Cartesian Product in Java

Question

I want to compute the cartesian product of an arbitrary number of nonempty sets in Java.

I\'ve wrote that iterative code...

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Answer 1

I've written a solution that doesn't require you to fill up a large collection in memory. Unfortunately, the code required is hundreds of lines long. You may have to wait until it appears in the Guava project (https://github.com/google/guava), which I hope will be by the end of the year. Sorry. :(

Note that you may not need such a utility if the number of sets you're cartesian-producting is a fixed number known at compile time -- you could just use that number of nested for loops.

EDIT: the code is released now.

Sets.cartesianProduct()

I think you'll be very happy with it. It only creates the individual lists as you ask for them; doesn't fill up memory with all MxNxPxQ of them.

If you want to inspect the source, it's here.

Enjoy!