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(Kalkulator Sederhana)),
    	body: Calculator(),
  	),
	);
  }
}

class Calculator extends StatefulWidget {
  @override
  _CalculatorState createState() => _CalculatorState();
}

class _CalculatorState extends State<Calculator> {
  final TextEditingController _number1Controller = TextEditingController();
  final TextEditingController _number2Controller = TextEditingController();
  String _result = ;

  void _calculate(String operation) {
	double number1 = double.parse(_number1Controller.text);
	double number2 = double.parse(_number2Controller.text);
	double calculationResult;

	if (operation == add) {
  	calculationResult = number1 + number2;
	} else {
  	calculationResult = number1 - number2;
	}

	setState(() {
  	_result = Hasil: $calculationResult;
	});
  }

  @override
  Widget build(BuildContext context) {
	return Column(
  	children: [
    	TextField(
      	controller: _number1Controller,
      	decoration: InputDecoration(labelText: Masukkan Angka Pertama),
      	keyboardType: TextInputType.number,
    	),
    	TextField(
      	controller: _number2Controller,
      	decoration: InputDecoration(labelText: Masukkan Angka Kedua),
      	keyboardType: TextInputType.number,
    	),
    	Row(
      	mainAxisAlignment: MainAxisAlignment.spaceAround,
      	children: [
        	ElevatedButton(
          	onPressed: () => _calculate(add),
          	child: Text(Tambah),
        	),
        	ElevatedButton(
          	onPressed: () => _calculate(subtract),
          	child: Text(Kurang),
        	),
      	],
    	),
    	Text(_result),
  	],
	);
  }
}