question: @ SuppressWarnings ( "unchecked" ) @ Override public boolean containsKey ( Object key ) { java . lang . Comparable < K > object = comparator == null ? toComparable ( ( K ) key ) : null ; K keyK = ( K ) key ; Node < K , V > node = root ; while ( node != null ) { K [ ] keys = node . keys ; int left_idx = node . left_idx ; int result = object != null ? object . compareTo ( keys [ left_idx ] ) : - comparator . compare ( keys [ left_idx ] , keyK ) ; if ( result < 0 ) { node = node . left ; } else if ( result == 0 ) { return true ; } else { int right_idx = node . right_idx ; if ( left_idx != right_idx ) { result = cmp ( object , keyK , keys [ right_idx ] ) ; } if ( result > 0 ) { node = node . right ; } else if ( result == 0 ) { return true ; } else { int low = left_idx + 1 , mid = 0 , high = right_idx - 1 ; while ( low <= high ) { mid = ( low + high ) > > > 1 ; result = cmp ( object , keyK , keys [ mid ] ) ; if ( result > 0 ) { low = mid + 1 ; } else if ( result == 0 ) { return true ; } else { high = mid - 1 ; } } return false ; } } } return false ; }
target:  Returns whether this map contains the specified key.