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");
 }

CodePudding user response：

You can try this:

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

CodePudding user response：

Solution:

Below is an example to Future.delayed method :

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

// Here you can write your code
  
});

CodePudding user response：

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");
  });
 }

CodePudding user response：

I think it also possible to use Timer as well:

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

CodePudding user response：

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.
  }());