# operator [] method

V operator [] (Object key)
override

Returns the value for the given `key` or null if `key` is not in the map.

Some maps allow keys to have `null` as a value. For those maps, a lookup using this operator cannot distinguish between a key not being in the map and the key having a `null` value. Methods like containsKey or putIfAbsent can be used if the distinction is important.

## Implementation

    V operator [](Object key) {
      if (!_validKey(key)) return null;
      if (_root != null) {
        int comp = _splay(key);
        if (comp == 0) {
          return _root.value;
        }
      }
      return null;
    }