Split a list into two sublists in all possible ways

Question

I have a list of variable size, for example

[1, 2, 3, 4]

and I want to get every possible way to split this list into two:

Answer 1

A more low-level solution using bitwise arithmetic to count subsets that should be easy to translate to Java:

def sublists(xs):
    l = len(xs)
    for i in range(1 << l):
        incl, excl = [], []
        for j in range(l):
            if i & (1 << j):
                incl.append(xs[j])
            else:
                excl.append(xs[j])
        yield (incl, excl)