CODEWITHSUNDEEP
dart
Learning Code
Learning Code

Reputation: 45

Add wait time in dart

How can I add a wait time in dart/flutter. I have two blocks of code to be executed after an if else statement. I want to add some time between them because the first one got a message to display to the user.

if(test==true){
 print("Hello"};
 //wait time added here 
 print("This hello after 5 secondes");
 }

Upvotes: 0

Views: 1942

Answers (5)

lrn
lrn

Reputation: 71623

There is any number of ways to do it, depending on how you want it to work, and whether your function is already asynchronous.

In general, you cannot insert a delay into a function which isn't asynchronous, not without blocking everything else.

  • If you don't want anything to happen in-between, and don't mind blocking, you can use sleep from dart:io

    sleep(const Duration(seconds: 5));

    or if you are on the web, and don't have dart:io, you can busy-wait:

    var sw = Stopwatch()..start();
while (sw.elapsedMilliseconds < 5000) {}

    Both block any other computation from happening in the same isolate. The latter also spends a lot of CPU power doing it.

  • If your don't want to block (you usually don't), and your function is already asynchronous (returns a future, is marked async), you can easily insert a non-blocking pause:

    // before the pause
await Future.delayed(const Duration(seconds: 5));
// rest of function

    Consider making your function asynchronous if it isn't already.

  • If you don't want to block, but your function is not asynchronous, then you need to start an asynchronous operation, and put the rest of your function into that, so that it will execute later. Then your function returns (synchronously), so no-one will be able to wait for the delayed part to happen. You can use any of:

    Timer(const Duration(seconds: 5), () {
  // rest of function.
});

    or

    unawaited(Future.delayed(const Duration(seconds: 5), () {
  // rest of function.
}));

    or even introduce a local async function

    unawaited(() async {
   await Future.delayed(const Duration(seconds: 5));
   // rest of function.
}());

Upvotes: 3

hansels
hansels

Reputation: 23

I think it also possible to use Timer as well:

Timer(Duration(seconds: 5), () => print("This hello after 5 seconds"));

Upvotes: 0

david okoroafor
david okoroafor

Reputation: 363

you can use Future.delayed to acheive that.

if(test==true){
   print("Hello");
  Future.delayed(const Duration(seconds: 5), () {
    print("This hello after 5 secondes");
  });
 }

Upvotes: 0

Learning Code
Learning Code

Reputation: 45

Solution:

Below is an example to Future.delayed method :

Future.delayed(const Duration(seconds: 1,milliseconds: 600), () {

// Here you can write your code
  
});

Upvotes: 0

Petar Bivolarski
Petar Bivolarski

Reputation: 1757

You can try this:

Future.delayed(Duration(seconds: 5), () => print('This hello after 5 seconds'));

Upvotes: 0

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