add streams to main

Author: Max Steffen

1_dart/20_streams.dart

@@ -1,27 +1,41 @@
 import 'dart:async';
 
-void main(){
-  Stream numberStream = NumberGenerator().getStream.asBroadcastStream();
+void main() {
+  final numberGenerator = NumberGenerator();
+  final numberStream = numberGenerator.getStream.asBroadcastStream();
   //! broadcast -> can handle multiple subscribers
 
   StreamSubscription sub1 = numberStream.listen((event) {
-    print(event);
+    print('sub1: $event');
   });
-}
-
-class NumberGenerator {
-  int _counter = 0;
 
-  StreamController<int> _controller = StreamController<int>();
+  StreamSubscription sub2 = numberStream.listen((event) {
+    print('sub2: ${event * event}');
+  });
 
-  Stream<int> get getStream => _controller.stream;
+  Future.delayed(const Duration(seconds: 5), () {
+    sub1.cancel();
+    sub2.cancel();
+  });
+}
 
-  NumberGenerator(){
-    final timer = Timer.periodic(Duration(seconds: 1), (timer) { 
-      _controller.sink.add(_counter);
+class NumberGenerator {
+  NumberGenerator() {
+    final timer = Timer.periodic(const Duration(seconds: 1), (timer) {
+      _controller.add(_counter);
+      // _controller.sink.add(_counter);
       _counter++;
     });
 
-    Future.delayed(Duration(seconds: 10), () => timer.cancel());
+    Future.delayed(const Duration(seconds: 10), () {
+      timer.cancel();
+      _controller.close();
+    });
   }
-}
+
+  int _counter = 0;
+
+  final StreamController<int> _controller = StreamController<int>();
+
+  Stream<int> get getStream => _controller.stream;
+}