AppBar in Flutter

app_bar_demo_widget.dart

import 'package:flutter/material.dart';

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

enum MenuOptions {
  FILTERS,
  SETTINGS,
}

class AppBarDemoWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'AppBar Demo',
      home: Scaffold(
        appBar: AppBar(
          leading: IconButton(
            icon: Icon(Icons.menu),
            onPressed: () {
              //Do Something
            },
          ),
          title: Text('AppBar Demo'),
          actions: <Widget>[
            IconButton(
              icon: Icon(Icons.search),
              onPressed: () {
                //Do something
              },
            ),
            IconButton(
              icon: Icon(Icons.shopping_cart_rounded),
              onPressed: () {
                //Do something
              },
            ),
            PopupMenuButton(
              offset: Offset(0, 100),
              child: Padding(
                  padding: EdgeInsets.symmetric(horizontal: 8),
                  child: Icon(Icons.more_vert)),
              onSelected: (MenuOptions selectedOption) {
                //Do something
              },
              itemBuilder: (context) => [
                PopupMenuItem(
                  child: Text('Filters'),
                  value: MenuOptions.FILTERS,
                ),
                PopupMenuItem(
                  child: Text('Settings'),
                  value: MenuOptions.SETTINGS,
                ),
              ],
            ),
          ],
        ),
        body: Container(),
      ),
    );
  }
}

app_bar_demo_widget_theme.dart

import 'package:flutter/material.dart';

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


enum MenuOptions{
  FILTERS,
  SETTINGS
}

class AppBarDemoWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.purple,
        appBarTheme: Theme.of(context).appBarTheme.copyWith(
              centerTitle: true,
              elevation: 16,
              shadowColor: Colors.black,
            ),
        primaryTextTheme: Theme.of(context).primaryTextTheme.copyWith(
              headline6: TextStyle(
                fontSize: 30,
                fontWeight: FontWeight.bold,
                color: Colors.amber,
              ),
            ),
        primaryIconTheme: Theme.of(context).primaryIconTheme.copyWith(
              color: Colors.amberAccent,
            ),
      ),
      debugShowCheckedModeBanner: false,
      title: 'AppBar Demo App',
      home: Scaffold(
       appBar: AppBar(
        leading: IconButton(
          icon: Icon(Icons.menu),
          onPressed: () {
            //Do Something
          },
        ),
        title: Text('AppBar Demo'),
        
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.search),
            onPressed: () {
              //Do something
            },
          ),
          IconButton(
            icon: Icon(Icons.shopping_cart_rounded),
            onPressed: () {
              //Do something
            },
          ),
          PopupMenuButton(
            offset: Offset(0, 100),
            child: Padding(padding: EdgeInsets.symmetric(horizontal: 8),child: Icon(Icons.more_vert)),
            onSelected: (MenuOptions selectedOption){
              //Do something
            },
            itemBuilder: (context) => [
              PopupMenuItem(
                child: Text('Filters'),
                value: MenuOptions.FILTERS,
              ),
              PopupMenuItem(
                child: Text('Settings'),
                value: MenuOptions.SETTINGS,
              ),
            ],
          ),
         ],
      ),
       body: Container(),
      ),
    );
  }
}