praktikum_pertemuan_9

import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  double _angka = 0;
  double _hasil = 0;
  List<String> _ukuran = ["KM", "M"];
  var _ukuranSemula;
  var _ukuranKonversi;
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text("Pengonversi Panjang"),
        ),
        body: Container(
          padding: EdgeInsets.all(50),
          child: Column(
            children: [
              Text("Angka"),
              TextField(
                onChanged: (text) {
                  var bacaAngka = double.tryParse(text);
                  if (bacaAngka != null) {
                    setState(() {
                      _angka = bacaAngka;
                    });
                  } else {
                    setState(() {
                      _angka = 0;
                    });
                  }
                },
              ),
              Text("Dari"),
              DropdownButton(
                value: _ukuranSemula,
                items: _ukuran.map((String value) {
                  return DropdownMenuItem(
                    child: Text(value),
                    value: value,
                  );
                }).toList(),
                onChanged: (value) {
                  setState(() {
                    _ukuranSemula = value;
                  });
                },
              ),
              Text("Menjadi"),
              DropdownButton(
                value: _ukuranKonversi,
                items: _ukuran.map((String value) {
                  return DropdownMenuItem(
                    child: Text(value),
                    value: value,
                  );
                }).toList(),
                onChanged: (value) {
                  setState(() {
                    _ukuranKonversi = value;
                  });
                },
              ),
              ElevatedButton(onPressed: () => convert(), child: Text("UBAH")),
              Text(_hasil.toString()),
            ],
          ),
        ),
      ),
    );
  }

  void convert() {
    setState(() {
      if (_ukuranSemula == "KM" && _ukuranKonversi == "M") {
        _hasil = _angka * 1000;
      } else if (_ukuranSemula == "M" && _ukuranKonversi == "KM") {
        _hasil = _angka / 1000;
      } else {
        _hasil = _angka;
      }
    });
  }
}