CODEWITHSUNDEEP
androidflutterdart
Farwa
Farwa

Reputation: 7024

Flutter - How to check a value after delay in a listener?

Here's my code:

networkConnectivity.listen((value) async {
      print("Before: $value");
      await Future.delayed(const Duration(seconds: 5));
      print("Later: $value");
      if (!value) {
        ...
      } else {
        ..
      }
    });

Let's say the listener gets triggered when there's no internet and Before value is false. But even if Before value is already changed to true within 5 seconds, Later remains false.

Why am I not getting the updated value in this situation? What's the workaround?

Upvotes: 0

Views: 1245

Answers (2)

kounex
kounex

Reputation: 1715

Based on your latest response where you want to show a dialog once the listener calls the provided callback with false (no connection) and the callback won't be called with the value true within 5 seconds, the following approach might be what you want:

Timer noConnectivityTimer;

...

networkConnectivity.listen((value) async {
    if (!value && (noConnectivityTimer == null || !noConnectivityTimer.isActive)) {
        noConnectivityTimer = Timer(Duration(seconds: 5), () => showDialog(...));
    } else {
        noConnectivityTimer?.cancel();
        ...
    }
  },
);

What i did: making use of the Timer class where i can define a Duration where a callback (defined right after) will be called once the given duration has been reached - we will show the dialog there. But if our listener callback gets a value which is true, indicating we have a connection again, we want to cancel any running Timer so the dialog is only shown when we received a false value initially and no true value within 5 seconds. You might want to edit this as you need it in your app, this is just an example!

Upvotes: 2

Jon Mountjoy
Jon Mountjoy

Reputation: 4526

A variable's value won't change unless something changes it. In the code you provide, nothing change the value of 'value' between your two prints.

Presumably, what will happen when the connectivity changes, is that your code block will run again, with a new value in the 'value' variable.

Upvotes: 0

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