addListener method Null safety

void addListener(
  1. ValueChanged<RawKeyEvent> listener
)

Register a listener that is called every time the user presses or releases a hardware keyboard key.

Since the listeners have no way to indicate what they did with the event, listeners are assumed to not handle the key event. These events will also be distributed to other listeners, and to the keyEventHandler.

Most applications prefer to use the focus system (see Focus and FocusManager) to receive key events to the focused control instead of this kind of passive listener.

Listeners can be removed with removeListener.

Implementation

void addListener(ValueChanged<RawKeyEvent> listener) {
  _listeners.add(listener);
}