Alert Manager

main.dart

/*
 * author: malinkaphann@gmail.com
 * create an alert widget
 * */
import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyAlert(),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello, World!', style: Theme.of(context).textTheme.headline4);
  }
}

/*
 * SEVERITY
 * - INFO: show an alert in normal case
 * - ERROR: show an alert when error or crash
 * 
 * @TODO: move this enum into utility class
 */
enum SEVERITY { INFO, ERROR }

/*
 * MyAlert is a stateful widget
 * 1- type: INFO or ERROR
 * 2- title
 * 3- message
 */
class MyAlert extends StatefulWidget {
  @override
  _MyAlertState createState() => _MyAlertState();
}

/*
 * _MyAlertState is a state for MyAlert
 */

class _MyAlertState extends State<MyAlert> {
  SEVERITY type;
  String title;
  String message;

  @override
  Widget build(BuildContext context) {
    return RaisedButton(
      onPressed: () {
        this._showMyDialog();
      },
      child: const Text('show alert box', style: TextStyle(fontSize: 20)),
    );
  }

  /*
   * to show alert box
   */
  Future<void> _showMyDialog() async {
    return showDialog<void>(
      context: context,
      barrierDismissible: false, // user must tap button!
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('here is title'),
          content: SingleChildScrollView(
            child: ListBody(
              children: <Widget>[
                Text('message is here')
              ],
            ),
          ),
          actions: <Widget>[
            TextButton(
              child: Text('button is here'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }
}