code: public static int binarySearch(int[] index, int key, int begin, int end) {
          return java.util.Arrays.binarySearch(index, begin, end, key);
      }
docs: Searches for a key in a subset of a sorted array.
  
  @param index
  Sorted array of integers
  @param key
  Key to search for
  @param begin
  Start posisiton in the index
  @param end
  One past the end position in the index
  @return Integer index to key. A negative integer if not found