How To Prevent Button Double Tap Using 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: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() {
    return new MyHomePageState();
  }
}

class MyHomePageState extends State<MyHomePage> {
  bool _isButtonTapped = false;

  _onTapped() {
    setState(() => _isButtonTapped =
    !_isButtonTapped);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.deepPurple[900],
        title: Text('Prevent Button Double Tap'),
      ),
      body: Center(
        child: RaisedButton(
          color: Colors.deepPurple[900],
          child: Text('Tap Once',style: TextStyle(color: Colors.white),),
          onPressed: _isButtonTapped
              ? null
              : _onTapped,
        ),
      ),
    );
  }
}