Stream Builder in Flutter

Priyanka Kumari

28 April 2023

Use Stream Builder in Flutter class is a widget for helping the user to make a selection in material design. If the future is created at the same time as the StreamBuilder, then every time the StreamBuilder’s parent is rebuilt, the asynchronous task will be restarted.

In Flutter, The Stream Builder widget rebuilding is scheduled by each interaction, using State.setState, but it is otherwise decoupled from the timing of the stream.

You can become better acquainted with the Flutter app development services page.

To implement the Stream Builder do follow the steps mentioned below.

1.) Create a Scaffold.

2.) Create the Timing schedule.

3.) Use the StreamBuilder widget.

1.) Create a Scaffold. :

Inside Scaffold widgets, it Implements the basic material design visual layout structure. First, initialize the main app as a stateless widget.

This class provides APIs for showing drawers and bottom sheets. We can add the background color inside the scaffold widget.

It also supports special Material Design components, such as Drawers, AppBars, and SnackBars.

  void main() {
    runApp(const MyApp());
  }

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        title: 'StreamBuilder Demo',
        theme: ThemeData(
        primarySwatch: Colors.blue,
    ),
    home: _DemoStreamBuilderScreen(),
    );
  }
}

void main() {

runApp(const MyApp());

}

class MyApp extends StatelessWidget {

const MyApp({Key? key}) : super(key: key);

// This widget is the root of your application.

@override

Widget build(BuildContext context) {

return MaterialApp(

debugShowCheckedModeBanner: false,

title: 'StreamBuilder Demo',

theme: ThemeData(

primarySwatch: Colors.blue,

home: _DemoStreamBuilderScreen(),

);

}

2.) Create the Timing schedule.

Now, For timing, we can create a widget rebuilding scheduled by the completion of the future, using State.setState, but is otherwise decoupled from the timing of the future. The builder callback is called at the discretion of the Flutter pipeline, and will thus receive a timing-dependent sub-sequence of the snapshots that represent the interaction with the future.

  Stream<int> counter() async* {
    int i = 0;
    while (true) {
      await Future.delayed(Duration(seconds: 1));
      yield i++;
      if (i == 100) break;
    }
  }

Stream<int> counter() async* {

int i = 0;

while (true) {

await Future.delayed(Duration(seconds: 1));

yield i++;

if (i == 100) break;

}

3.) Use the StreamBuilder widget.

In StreamBuilder, it calls the future capacity to wait for the outcome, and when it creates the outcome it calls the builder function where we assemble the widget.

The full code is mentioned below.

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Stream Builder Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: _DemoStreamBuilderScreen(),
    );
  }
}
class _DemoStreamBuilderScreen extends StatelessWidget {
  Stream<int> counter() async* {
    int i = 0;
    while (true) {
      await Future.delayed(Duration(seconds: 1));
      yield i++;
      if (i == 100) break;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: StreamBuilder<int>(
        stream: counter(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return Text("Intializing...");
          }
          return Text("${snapshot.data}", style: TextStyle(fontSize: 40));
        },
      ),
    );
  }
}

import 'package:flutter/material.dart';

void main() {

runApp(const MyApp());

}

class MyApp extends StatelessWidget {

const MyApp({Key? key}) : super(key: key);

@override

Widget build(BuildContext context) {

return MaterialApp(

debugShowCheckedModeBanner: false,

title: 'Stream Builder Demo',

theme: ThemeData(

primarySwatch: Colors.blue,

home: _DemoStreamBuilderScreen(),

);

}

class _DemoStreamBuilderScreen extends StatelessWidget {

Stream<int> counter() async* {

int i = 0;

while (true) {

await Future.delayed(Duration(seconds: 1));

yield i++;

if (i == 100) break;

}

@override

Widget build(BuildContext context) {

return Center(

child: StreamBuilder<int>(

stream: counter(),

builder: (context, snapshot) {

if (!snapshot.hasData) {

return Text("Intializing...");

}

return Text("${snapshot.data}", style: TextStyle(fontSize: 40));

);

}

We can now run the app on how to create Stream Builder in a flutter.

Finally, we have implemented the flow of creating Stream Builder in a flutter.

Hope this blog helps you to create Stream Builder in a flutter.

So, I hope it will help you out in understanding and get a brief idea about it.

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That’s all.

Thank you very much.