Stateless widget

 import 'package:flutter/material.dart';

void main() {

  runApp(MyApp());

}

class MyApp extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    return MaterialApp(

      title: 'Flutter App',

      debugShowCheckedModeBanner: false,

      theme: ThemeData(

        primaryColor: Colors.green,

        accentColor: Colors.yellow,

      ),

      home: Scaffold(

        appBar: AppBar(

          title: Text('Flutter'),

          backgroundColor: Colors.green,

        ),

        body: Center(

          child: Column(

            crossAxisAlignment: CrossAxisAlignment.start,

            mainAxisAlignment: MainAxisAlignment.center,

            children: <Widget>[

              Text('I am Dipanshu'),

              Text('Persuing BCA'),

              Icon(Icons.mood),

              RaisedButton(

                onPressed: () {},

                child: Text('Sign Up'),

                color: Colors.orange,

                splashColor: Colors.pink,

              )

            ],

          ),

        ),

        floatingActionButton: FloatingActionButton(

            onPressed: () {},

            child: Icon(

              Icons.add_a_photo,

              color: Colors.pink,

            )),

      ),

    );

  }

}