public static void sort(Integer[] array) {
        // save original reference
        Integer[] erg = array;
        Integer[] helperArray = new Integer[array.length];
        int mask = 1;
        // Only positive numbers allowed..
        for(int i = 0; i < 31; i++) {
            int pos = 0;
            for(int j = 0; j < array.length; j++) {
                if ((array[j] & mask) == 0)
                    helperArray[pos++] = array[j];
            }
            for(int j = 0; j < array.length; j++) {
                if ((array[j] & mask) != 0)
                    helperArray[pos++] = array[j];
            }
            assert pos == array.length;
            mask <<= 1;
            Integer[] temp = array;
            array = helperArray;
            helperArray = temp;
        }
        System.arraycopy(array, 0, erg, 0, erg.length);
    }