AppBar With Scaffold

 AppBar

With 

Scaffold

import 'package:flutter/material.dart';

void main(){
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: Text("App Bar Widget"),
        backgroundColor: Colors.purple.withOpacity(.50),
      ),    // AppBar
    ),
  ),    💪 // MaterialApp
  );
}