Dart by Example: Streams

  1. import 'dart:async';
  3. main() {
  4.   // creates a single subscription stream
  5.   new Stream.fromIterable([1, 3, 5]).listen((i) {
  6.     print('s1: $i');
  7.   });
  9.   // New streams can created from other streams, using
  10.   // using methods like where(), map(), expand(), take(), or skip()
  11.   new Stream.periodic(new Duration(milliseconds: 300))
  12.       .take(3)
  13.       .listen((_) => print('s2: tick!'));
  15.   new Stream.fromIterable([1, 2, 5]).map((n) => n * 2).listen((n) => print('s3: $n'));
  17.   // Broadcast streams can be listened to by multiple consumers.
  18.   var sc = new StreamController.broadcast();
  19.   var broadcastStream = sc.stream;
  20.   broadcastStream.listen((v) => print('s4: $v'));
  21.   broadcastStream.listen((v) => print('s4: $v'));
  22.   sc.add(1);
  23.   sc.add(2);
  24. }
  25.  
  1. $ dart streams.dart
  2. s1: 1
  3. s3: 2
  4. s4: 1
  5. s4: 1
  6. s1: 3
  7. s3: 4
  8. s4: 2
  9. s4: 2
  10. s1: 5
  11. s3: 10
  12. s2: tick!
  13. s2: tick!
  14. s2: tick!

by @jryanio | source | license