Java ArrayList Choose N elements

Say I have an ArrayList containing the elements {1,2,3,4}, and I want to enumerate all pos开发者_如何转开发sible combinations of two elements in the ArrayList. i.e. (1,2), (1,3), (1,4), (2,3), (2,4), (3,4). What is the most elegant way of going about doing this?

Nested for loops would work:

for (int i = 0; i < arrayList.size(); ++i) {
    for (int j = i + 1; j < arrayList.size(); ++j) {
        // Use arrayList.get(i) and arrayList.get(j).
    }
}