How can I dismiss the on screen keyboard?

I am collecting user input with a TextFormField and when the user presses a FloatingActionButton indicating they are done, I want to dismiss the on screen keyboard.

How do I make the keyboard go away automatically?

import 'package:flutter/material.dart';

class MyHomePage extends StatefulWidget {
  MyHomePageState createState() => new MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  TextEditingController _controller = new TextEditingController();

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.send),
        onPressed: () {
          setState(() {
            // send message
            // dismiss on screen keyboard here
            _controller.clear();
          });
        },
      ),
      body: new Container(
        alignment: FractionalOffset.center,
        padding: new EdgeInsets.all(20.0),
        child: new TextFormField(
          controller: _controller,
          decoration: new InputDecoration(labelText: 'Example Text'),
        ),
      ),
    );
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new MyHomePage(),
    );
  }
}

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

Solution

For Flutter version 2 or later :

Since Flutter 2 with null safety this is the best way:

FocusManager.instance.primaryFocus?.unfocus();

Note: using old ways leads to some problems like keep rebuild states;

For Flutter version < 2 :

As of Flutter v1.7.8+hotfix.2, the way to go is:

FocusScope.of(context).unfocus();

Comment on PR about that:

Now that #31909 (be75fb3) has landed, you should use FocusScope.of(context).unfocus() instead of FocusScope.of(context).requestFocus(FocusNode()), since FocusNodes are ChangeNotifiers, and should be disposed properly.

-> DO NOT use ̶r̶e̶q̶u̶e̶s̶t̶F̶o̶c̶u̶s̶(̶F̶o̶c̶u̶s̶N̶o̶d̶e̶(̶)̶ anymore.

 F̶o̶c̶u̶s̶S̶c̶o̶p̶e̶.̶o̶f̶(̶c̶o̶n̶t̶e̶x̶t̶)̶.̶r̶e̶q̶u̶e̶s̶t̶F̶o̶c̶u̶s̶(̶F̶o̶c̶u̶s̶N̶o̶d̶e̶(̶)̶)̶;̶