alert_dialog_example.dart

import 'package:flutter/material.dart';
 
Future<void> _ackAlert(BuildContext context) {
  return showDialog<void>(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Not in stock'),
        content: const Text('This item is no longer available'),
        actions: <Widget>[
          FlatButton(
            child: Text('Ok'),
            onPressed: () {
              Navigator.of(context).pop();
            },
          ),
        ],
      );
    },
  );
}
enum ConfirmAction { CANCEL, ACCEPT }
Future<ConfirmAction> _asyncConfirmDialog(BuildContext context) async {
  return showDialog<ConfirmAction>(
    context: context,
    barrierDismissible: false, // user must tap button for close dialog!
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Reset settings?'),
        content: const Text(
            'This will reset your device to its default factory settings.'),
        actions: <Widget>[
          FlatButton(
            child: const Text('CANCEL'),
            onPressed: () {
              Navigator.of(context).pop(ConfirmAction.CANCEL);
            },
          ),
          FlatButton(
            child: const Text('ACCEPT'),
            onPressed: () {
              Navigator.of(context).pop(ConfirmAction.ACCEPT);
            },
          )
        ],
      );
    },
  );
}
 
Future<String> _asyncInputDialog(BuildContext context) async {
  String teamName = '';
  return showDialog<String>(
    context: context,
    barrierDismissible: false, // dialog is dismissible with a tap on the barrier
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Enter current team'),
        content: new Row(
          children: <Widget>[
            new Expanded(
                child: new TextField(
              autofocus: true,
              decoration: new InputDecoration(
                  labelText: 'Team Name', hintText: 'eg. Juventus F.C.'),
              onChanged: (value) {
                teamName = value;
              },
            ))
          ],
        ),
        actions: <Widget>[
          FlatButton(
            child: Text('Ok'),
            onPressed: () {
              Navigator.of(context).pop(teamName);
            },
          ),
        ],
      );
    },
  );
}
 
enum Departments { Production, Research, Purchasing, Marketing, Accounting }
 
Future<Departments> _asyncSimpleDialog(BuildContext context) async {
  return await showDialog<Departments>(
      context: context,
      barrierDismissible: true,
      builder: (BuildContext context) {
        return SimpleDialog(
          title: const Text('Select Departments '),
          children: <Widget>[
            SimpleDialogOption(
              onPressed: () {
                Navigator.pop(context, Departments.Production);
              },
              child: const Text('Production'),
            ),
            SimpleDialogOption(
              onPressed: () {
                Navigator.pop(context, Departments.Research);
              },
              child: const Text('Research'),
            ),
            SimpleDialogOption(
              onPressed: () {
                Navigator.pop(context, Departments.Purchasing);
              },
              child: const Text('Purchasing'),
            ),
            SimpleDialogOption(
              onPressed: () {
                Navigator.pop(context, Departments.Marketing);
              },
              child: const Text('Marketing'),
            ),
            SimpleDialogOption(
              onPressed: () {
                Navigator.pop(context, Departments.Accounting);
              },
              child: const Text('Accounting'),
            )
          ],
        );
      });
}
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
      appBar: AppBar(
        title: Text("Dialog"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new RaisedButton(
              onPressed: () {
                _ackAlert(context);
              },
              child: const Text("Ack Dialog"),
            ),
            new RaisedButton(
              onPressed: () async {
                final ConfirmAction action = await _asyncConfirmDialog(context);
                print("Confirm Action $action" );
              },
              child: const Text("Confirm Dialog"),
            ),
            new RaisedButton(
              onPressed: () async {
                final Departments deptName = await _asyncSimpleDialog(context);
                print("Selected Departement is $deptName");
              },
              child: const Text("Simple dialog"),
            ),
            new RaisedButton(
              onPressed: () async {
                final String currentTeam = await _asyncInputDialog(context);
                print("Current team name is $currentTeam");
              },
              child: const Text("Input Dialog"),
            ),
          ],
        ),
      ),
    );
  }
}
 
void main() {
  runApp(new MaterialApp(home: new MyApp()));
}