code: @SuppressWarnings("unchecked")
  	public <T> void sort(Arr arr, Comparator<T> c) {
  		int l = arr.getLength();
  		Object[] objs = new Object[l];
  		for (int i=0; i<l; i++) {
  			objs[i] = arr.get(i);
  		}
  		Arrays.sort((T[])objs, c);
  		for (int i=0; i<l; i++) {
  			arr.put(i, objs[i]);
  		}
  	}
docs: can lead to classcastexception if comparator is not of the right type