How to automatically show an alert dialog without pressing a button in Flutter?

Issue

I implemented the alert dialog in the initstate() method but Init state is only called once. In my case I want the alert to appear automatically every time a variable value changes for exemple. ( I need it to suddenly pop up during using the app)

Solution

You could use a ValueNotifier and a ValueListenableBuilder so that every time the value in the ValueNotifier changes, the ValueListenableBuilder rebuilds and shows a dialog, like so:

class MyWidget extends StatelessWidget {
  
  ValueNotifier<int> dialogTrigger = ValueNotifier(0);

  
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextButton(
          onPressed: () {
            var random = Random();
            dialogTrigger.value = random.nextInt(100);
          },
          child: const Text('Click me and change a value')
        ),
        Expanded(
          child: ValueListenableBuilder(
          valueListenable: dialogTrigger,
          builder: (ctx, value, child) {

            Future.delayed(const Duration(seconds: 0), () {
              showDialog(
                context: ctx,
                builder: (ctx) {
                  return AlertDialog(
                    title: const Text('Dialog'),
                    content: Text('Hey! I got a $value'),
                  );
                });
            });
            
            return const SizedBox();
          })
        )
      ]
    );
  }
}

(Again, I'm only adding a button to change the value, not to launch the dialog. That way you can programmatically change the value, which eventually launches the dialog). See if that works for your purposes.

Answered By - Roman Jaquez