Flutter StreamBuilder vs FutureBuilder

Issue

What is the main difference between StreamBuilder and FutureBuilder.

  • What to use and when to use?

  • What are the tasks they are intended to perform?

  • How each of them listens to changes in a dynamic list?

Solution

Both StreamBuilder and FutureBuilder have the same behavior: They listen to changes on their respective object. And trigger a new build when they are notified
of a new value.

So in the end, their differences are how the object they listen to works.

Future is like Promise in JS or Task in c#. They are the representation of an asynchronous request. Futures have one and only one response. A common usage of Future is to handle HTTP calls. What you can listen to on a Future is its state. Whether it’s done, finished with success, or had an error. But that’s it.

Stream on the other hand is like async Iterator in JS. This can be assimilated to a value that can change over time. It usually is the representation of web-sockets or events (such as clicks). By listening to a Stream you’ll get each new value and also if the Stream had an error or completed.

How each of them listens to changes in a dynamic list?

A Future can’t listen to a variable change. It’s a one-time response. Instead, you’ll need to use a Stream.

Answered By – Rémi Rousselet

Answer Checked By – Jay B. (FlutterFixes Admin)

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