Learn Simple Alert Dialog Box In Flutter Android App

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
            appBar: AppBar(
              centerTitle: true,
                backgroundColor: Colors.indigo,
                title: Text('Simple Alert Dialog Box')
            ),
            body: Center(
                child: Alert()
            )
        )
    );
  }
}

class Alert extends StatefulWidget {

  AlertState createState() => AlertState();

}

class AlertState extends State {

  showAlert(BuildContext context) {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: new Text('Alert Message.'),
          actions: <Widget>[
            FlatButton(
              child: new Text("OK"),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child:
        RaisedButton(
          onPressed: () => showAlert(context),
          child: Text('Show Alert Dialog BOx'),
          textColor: Colors.white,
          color: Colors.indigo,
          padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
        ),
      ),
    );
  }
}