CODEWITHSUNDEEP
widgetflutter
Rainer Schlund
Rainer Schlund

Reputation: 95

Trying to understand widget-object in flutter democode

I'm just trying to learn flutter and there's a piece of code in the flutter demo code, that you get when creating a new flutter project, that i don't understand :

title: new Text(widget.title)

I don't understand where widget comes from, as it is nowhere declared, defined or initialized. It refers to this Text:

home: new MyHomePage(title: 'Flutter Demo Home Page')

but why, has it something to do with context? And if its something predefined, how and where can i use it. As everything in flutter is a Widget it's hard to ask Google for that problem. 

import 'package:flutter/material.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
   });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              'You have pushed the button this many times:',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
   );
  }
}

Upvotes: 3

Views: 1876

Answers (1)

Andrii Turkovskyi
Andrii Turkovskyi

Reputation: 29438

MyHomePage has final field title, which you declare in constructor - MyHomePage(title: 'Flutter Demo Home Page')``_MyHomePageState - it's a state of stateful widget. In every state you can use widget to get your StatefulWidget

Upvotes: 5

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