@Override public boolean containsKey(Object key){
  if (key == null) {
    return false;
  }
  K[] keys=_keys;
  for (int i=_size - 1; i >= 0; i--) {
    K testKey=keys[i];
    if (key.equals(testKey)) {
      return true;
    }
  }
  return false;
}

@ Override public boolean containsKey ( Object key ) { if ( key == null ) { return false ; } K [ ] keys = _keys ; for ( int i = _size - 1 ; i >= 0 ; i -- ) { K testKey = keys [ i ] ; if ( key . equals ( testKey ) ) { return true ; } } return false ; }
returns true if the map contains the value .
