Can't change flutter theme color

Question

I need to change the flutter theme color, but when I tried then run my app it's show nothing to change. I don't know why.

I have tried this way:

import 'package:flutter/material.dart';

import 'pages/home_page.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
      themeMode: ThemeMode.dark,
      theme: ThemeData(primarySwatch: Colors.deepPurple),
      darkTheme: ThemeData(
          brightness: Brightness.dark, primarySwatch: Colors.deepPurple),
    );
  }
}

when I change like this way, then still show me default blue color.

flutter version: 2.2.1

Any suggestion please.

Answer 1

with this code:

   import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Title",
      theme: ThemeData(primarySwatch: Colors.deepPurple),
      darkTheme: ThemeData(
          brightness: Brightness.dark, primarySwatch: Colors.deepPurple),
      home: Test(),
    );
  }
}

class Test extends StatelessWidget {
  const Test({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("SomeText"),
      ),
      body: Center(child: Text("Center Text",)),
    );
  }
}

I get This result. (Flutter 1.22.5)