listen for stream and print value in dart main function

Question

I want to print data.length after listening to this stream but the program executed synchronously. How can I listen to this data stream without using the await-for syntax

void main() async {
  final file = File('assets/text_long.txt');
  final stream = file.openRead();

  stream.listen(
    (data) {
      print(data.length);
    },
  );
}

Here is the output:

Exited (1)

await didn't work: Uses 'await' on an instance of 'StreamSubscription', which is not a subtype of 'Future'. — zex_rectooor, Mar 27 '23 at 13:13

score 1 · Accepted Answer · answered Mar 27 '23 at 13:17

1

Use asFuture method.

  final file = File('assets/text_long.txt');
  final stream = file.openRead();

  final streamSubscription = stream.listen(
    (data) {
      print(data.length);
    },
  );
  await streamSubscription.asFuture();

answered Mar 27 '23 at 13:17

zex_rectooor

692
7
26

score 0 · Answer 2 · answered Mar 26 '23 at 13:49

0

Use await keyword.

await stream.listen(
    (data) {
      print(data.length);
    },
  );

answered Mar 26 '23 at 13:49

Hoa Le

174
4

It didn't work : Uses 'await' on an instance of 'StreamSubscription', which is not a subtype of 'Future'. – zex_rectooor Mar 27 '23 at 13:13

listen for stream and print value in dart main function

2 Answers2