DART

flutter close dialog

showDialog(
    context: context,
    builder: (_) {
      return AlertDialog(
        title: Text('Wanna Exit?'),
        actions: [
          FlatButton(
            onPressed: () => Navigator.pop(context, false), // passing false
            child: Text('No'),
          ),
          FlatButton(
            onPressed: () => Navigator.pop(context, true), // passing true
            child: Text('Yes'),
          ),
        ],
      );
    }).then((exit) {
  if (exit == null) return;

  if (exit) {
    // user pressed Yes button
  } else {
    // user pressed No button
  }
});

show dialog close flutter

  BuildContext dialogContext; // <<----
  showDialog(
    context: context, // <<----
    barrierDismissible: false,
    builder: (BuildContext context) {
      dialogContext = context;
      return Dialog(
        child: new Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            new CircularProgressIndicator(),
            new Text("Loading"),
          ],
        ),
      );
    },
  );

  await _longOperation();
  Navigator.pop(dialogContext); // <<----

flutter show dialog on start

  import 'dart:async';
  import 'package:flutter/material.dart';

  void main() {
    runApp(new MyApp());
  }

  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
          title: 'Trial',
          home: Scaffold(
              appBar: AppBar(title: Text('List scroll')), body: new MyHome()));
    }
  }

  class MyHome extends StatelessWidget { // Wrapper Widget
    @override
    Widget build(BuildContext context) {
      Future.delayed(Duration.zero, () => showAlert(context));
      return Container(
        child: Text("Hello world"),
      );
    }

    void showAlert(BuildContext context) {
      showDialog(
          context: context,
          builder: (context) => AlertDialog(
                content: Text("hi"),
              ));
    }
  }

how to close alertdialog flutter

showDialog(
            context: context,
            child: new AlertDialog(
              title: const Text("Location disabled"),
              content: const Text(
                  """
Location is disabled on this device. Please enable it and try again.
                  """),
              actions: [
                new FlatButton(
                  child: const Text("Ok"),
                  onPressed: _dismissDialog,
                ),
              ],
            ),
        );