Syntax of StreamBuilder

StreamBuilder<T>(
  stream: yourStream, // The stream to listen to
  initialData: initialData, // Optional initial data while waiting for the first event
  builder: (BuildContext context, AsyncSnapshot<T> snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return YourLoadingWidget(); // Display a loading indicator while waiting for data
    } else if (snapshot.hasError) {
      return YourErrorWidget(error: snapshot.error); // Handle errors
    } else if (!snapshot.hasData) {
      return YourNoDataWidget(); // Handle the case when there's no data
    } else {
      return YourDataWidget(data: snapshot.data); // Display your UI with the data
    }
  },
)

Here we are going to see a simple example of a StreamBuilder in Flutter that listens to a stream of numbers and displays the latest number in real-time:

Required Tools

• To build this app, you need the following items installed on your machine:
• Visual Studio Code / Android Studio
• Android Emulator / iOS Simulator / Physical Device device.
• Flutter Installed
• Flutter plugin for VS Code / Android Studio.

A sample video is given below to get an idea about what we are going to do in this article.

A StreamBuilder in Flutter is used to listen to a stream of data and rebuild its widget subtree whenever new data is emitted by the stream. It’s commonly used for real-time updates, such as when working with streams of data from network requests, databases, or other asynchronous sources. In this article, we are going to see an example of a Streambuilder Widget by taking an Example.