code: public static int[] toIntArray(Collection<Integer> items) {
  		int[] result = new int[items.size()];
  		int i = 0;
  		for (Integer v : items) {
  			result[i++] = v;
  		}
  		return result;
  	}
docs: Convert a collection of Integers into an int array.
  
  @param items
  @return