focus.dart

import 'package:flutter/material.dart';

class ExampleLoginFocus extends StatefulWidget {
  @override
  _ExampleLoginFocusState createState() => _ExampleLoginFocusState();
}

class _ExampleLoginFocusState extends State<ExampleLoginFocus> {
  bool _obscureText = true;

  String _password;

  void _toggle() {
    setState(() {
      _obscureText = !_obscureText;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Sample"),
      ),
      body: Listener(
        onPointerUp: (e) {
          FocusScope.of(context).requestFocus(FocusNode());
        },
        child: new Container(
          child: new Column(
            children: <Widget>[
              new TextField(
                decoration: const InputDecoration(
                    labelText: 'Password',
                    icon: const Padding(
                        padding: const EdgeInsets.only(top: 15.0),
                        child: const Icon(Icons.lock))),

                //validator: (val) => val.length < 6 ? 'Password too short.' : null,
                onChanged: (val) => _password = val,
                obscureText: _obscureText,
              ),
              new FlatButton(
                  onPressed: _toggle,
                  child: new Text(_obscureText ? "Show" : "Hide"))
            ],
          ),
        ),
      ),
    );
  }
}