operator [] method

@override T? operator [](Object? key)

The value for the given key, or null if key is not in the map.

Some maps allow 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 being there with a null value. Methods like containsKey or putIfAbsent can be used if the distinction is important.

Implementation

@override
T? operator [](Object? key) {
  if (key is String?) {
    return _normalized[key?.toLowerCase()];
  } else {
    return null;
  }
}