import package:flutter/material.dart;

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
	return MaterialApp(
  	home: Scaffold(
    	appBar: AppBar(title: Text(Hitung Luas Persegi)),
    	body: MyHomePage(),
  	),
	);
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final _sideController = TextEditingController();
  double _area = 0.0;

  void _calculateArea() {
	setState(() {
  	double side = double.parse(_sideController.text);
  	_area = side * side;
	});
  }

  @override
  Widget build(BuildContext context) {
	return Column(
  	children: [
    	TextField(
      	controller: _sideController,
      	decoration: InputDecoration(labelText: Masukkan panjang sisi),
      	keyboardType: TextInputType.number,
    	),
    	ElevatedButton(
      	onPressed: _calculateArea,
      	child: Text(Hitung Luas),
    	),
    	Text(Luas Persegi: $_area),
  	],
	);
  }
}