I am new to dart and flutter, when i am using Stream, i found this function
StreamSubscription<T> listen(void onData(T event)?,
{Function? onError, void onDone()?, bool? cancelOnError});
Can someone tell me what does the '?' mean here?
Question mark after function parameter in dart
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1 Answers
As of Dart 2.12, the language supports null safety. Here, ? explicitly states that a variable/parameter may be null.
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