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How do you use Future.delayed() in Dart? Give an example.

Parthiban Kannan
Updated on December 6, 2025

1 min read

Future.delayed() is one of the simplest and most useful ways in Dart to create a delay or simulate an asynchronous operation like an API call or background task. Basically, it allows you to run a piece of code after a specific duration, without blocking the rest of the program.

The syntax is:

📄
filename.dart 
Future.delayed(Duration duration, [FutureOr Function()? computation])

So you pass the time to wait and optionally a function that runs after the delay.

For example:

📄
filename.dart 
void main() {
  print("Task 1 started");

  Future.delayed(Duration(seconds: 2), () {
    print("Task 2 executed after 2 seconds");
  });

  print("Task 3 started immediately");
}

When you run this, the output will be:

📄
filename.dart 
Task 1 started  
Task 3 started immediately  
Task 2 executed after 2 seconds

This clearly shows that Dart doesn’t block the thread — while waiting for the delay, other code keeps running.

In one of my Flutter projects, I used Future.delayed() to display a splash screen for a few seconds before navigating to the home screen. Something like this:

📄
filename.dart 
@override
void initState() {
  super.initState();
  Future.delayed(Duration(seconds: 3), () {
    Navigator.pushReplacementNamed(context, '/home');
  });
}

Here, the delay creates a smooth transition between screens without freezing the UI.

Another use case is simulating API calls while testing — instead of actually calling a backend, I can use Future.delayed() to mimic a network response time.

One challenge I faced was accidentally using it in tight loops, which can quickly queue up many delayed tasks — so I had to make sure delays were used thoughtfully, especially in periodic or timer-based logic.

If I need more control (like cancelling or repeating delays), I might use a Timer instead.

So overall, Future.delayed() is a neat way to simulate asynchronous behavior or introduce controlled waiting in Dart without blocking the main thread.

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