Printing all possible subsets of a list

Question

I have a List of elements (1, 2, 3), and I need to get the superset (powerset) of that list (without repeating elements). So basically I need to create a List of Lists that

Answer 1

I've noticed that answers are focused on the String list. Consequently, I decided to share more generic answer. Hope it'll be fouund helpful. (Soultion is based on another solutions I found, I combined it to a generic algorithem.)

/**
 * metod returns all the sublists of a given list
 * the method assumes all object are different
 * no matter the type of the list (generics)
 * @param list the list to return all the sublist of
 * @param 
 * @return list of the different sublists that can be made from the list object
 */
public static   List>getAllSubLists(Listlist)
{
    ListsubList;
    List>res = new ArrayList<>();
    List> indexes = allSubListIndexes(list.size());
    for(List subListIndexes:indexes)
    {
        subList=new ArrayList<>();
        for(int index:subListIndexes)
            subList.add(list.get(index));
        res.add(subList);
    }
    return res;
}
/**
 * method returns list of list of integers representing the indexes of all the sublists in a N size list
 * @param n the size of the list
 * @return list of list of integers of indexes of the sublist
 */
public static List> allSubListIndexes(int n) {
    List> res = new ArrayList<>();
    int allMasks = (1 << n);
    for (int i = 1; i < allMasks; i++)
    {
        res.add(new ArrayList<>());
        for (int j = 0; j < n; j++)
            if ((i & (1 << j)) > 0)
                res.get(i-1).add(j);

    }
    return res;
}