All possible combinations of an array

Question

I have an string array

{\"ted\", \"williams\", \"golden\", \"voice\", \"radio\"}

and I want all possible combinations of these keywords in

Answer 1

EDIT: As FearUs pointed out, a better solution is to use Guava's Sets.powerset(Set set).

EDIT 2: Updated links.

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Quick and dirty translation of this solution:

public static void main(String[] args) {

    List> powerSet = new LinkedList>();

    for (int i = 1; i <= args.length; i++)
        powerSet.addAll(combination(Arrays.asList(args), i));

    System.out.println(powerSet);
}

public static  List> combination(List values, int size) {

    if (0 == size) {
        return Collections.singletonList(Collections. emptyList());
    }

    if (values.isEmpty()) {
        return Collections.emptyList();
    }

    List> combination = new LinkedList>();

    T actual = values.iterator().next();

    List subSet = new LinkedList(values);
    subSet.remove(actual);

    List> subSetCombination = combination(subSet, size - 1);

    for (List set : subSetCombination) {
        List newSet = new LinkedList(set);
        newSet.add(0, actual);
        combination.add(newSet);
    }

    combination.addAll(combination(subSet, size));

    return combination;
}

Test:

$ java PowerSet ted williams golden
[[ted], [williams], [golden], [ted, williams], [ted, golden], [williams, golden], [ted, williams, golden]]
$