Flutter Keyboard Issues

main.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.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: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.green,
      ),
      debugShowCheckedModeBanner: false,
      home: MyHomePage(title: 'Flutter Keyboard Issues'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  var focusNode = new FocusNode();

  @override
  Widget build(BuildContext context) {
    var _blankFocusNode = new FocusNode();

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: GestureDetector(
        behavior: HitTestBehavior.opaque,
        onTap: () {
          // SystemChannels.textInput.invokeMethod('TextInput.hide');
          FocusScope.of(context).requestFocus(_blankFocusNode);
        },
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            SingleChildScrollView(
              child: Container(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: <Widget>[
                    Text(
                      'How to dismiss the keyboard!',
                      style: Theme.of(context).textTheme.display1,
                      textAlign: TextAlign.center,
                    ),
                    Row(
                      mainAxisSize: MainAxisSize.max,
                      children: <Widget>[
                        Text(
                          'Username',
                          style: Theme.of(context).textTheme.body1,
                        ),
                        Flexible(
                          child: TextField(
                            decoration: InputDecoration(
                                contentPadding: const EdgeInsets.all(10.0),
                                hintText: "john_doe"),
                          ),
                        )
                      ],
                    ),
                    // Container(padding: const EdgeInsets.only(top: 300.0),),
                    // Text('Hello', style: Theme.of(context).textTheme.display1,)
                  ],
                ),
              ),
            )
          ],
        ),
      ),
    );
  }
}