I have a List in GWT and I wish to sort it but GWT complains at runtime that it cannot be done.

    List<int[]> tuples = new LinkedList<int[]>();
    tuples.sort(new TupleComparator());

    class TupleComparator implements Comparator<int[]> {

        @Override
        public int compare(int[] o1, int[] o2) {
            int i = 0;
            int l = o1.length;
            while (i < l && o1[i] == o2[i]) {
                i++;
            }
            return (i == l ? 0 : o1[i] - o2[i]);
        }
    }

    [ERROR] [testgwtlistofint] - Line 116: The method sort(TupleComparator) 
    is undefined for the type List<int[]>