Streams represent a sequence of asynchronous events. Each event is either a data event, also called an element of the stream, or an error event, which is a notification that something has failed. When a stream has emitted all its events, a single "done" event will notify the listener that the end has been reached. In this lesson, we will learn how we can capture and handle streaming data, working with various Stream classes.

// Single Stream  StreamController
     
       controller = StreamController
      
       ();  // Setup listener  controller.stream.listen(    (data) => print('Received data: ${data.toUpperCase()}'),    onDone: () => print('done'),    onError: (e) => print('error $e')  );  // Emit event  controller.add('Hello');    controller.add('World');  // trigger error  controller.addError('Throwing this error');  // trigger done  await controller.close();  print('after done, return future, clean up');
      
     

 

// Broadcast Stream  StreamController
     
       controller2 = StreamController
      
       ();  Stream
       
         boradcast = controller2.stream.asBroadcastStream();    boradcast.listen((data) => print('Received data: $data'));                boradcast.listen((data) => print('Received data again: $data'));    controller2.add('Hello1');    controller2.add('World2');
       
      
     

 

// Future-based streams  Future
     
       result = HttpRequest.getString('https://swapi.co/api/people/1');  Stream
      
        resultStream = Stream.fromFuture(result);  resultStream.listen(    (data) => print('Got data: $data'),    onError: (e) => print(e.type),    onDone: () => print('No more data on stream.')  );    // Future-based multi streams  Future
       
         result2 = HttpRequest.getString('https://swapi.co/api/people/2');  Stream
        
          peopleStream = Stream.fromFutures([result, result2]);  peopleStream.listen(    (person) => print('=> Got person: $person'),        onDone: () => print('No more people on stream.')  );
        
       
      
     

 

// Typeahead  List
     
       chars = 'Dart is awesome'.split('');  Stream
      
        charStream = Stream.fromIterable(chars);  var idx = 0;  charStream.listen((char) {    Timer(Duration(milliseconds: idx * 200), () => print(char));    idx++;  });