mod for main.dart, list and grid class are separated

main2.dart

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'CRUD ListView Dan GridView',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MainPage(),
      debugShowCheckedModeBanner: false,
    );
  }
}

// bagian ListView dan GridView
class MainPage extends StatefulWidget {
  @override
  _MainPageState createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  List<String> kodePT = [];
  List<String> namaPT = [];
  List<String> alamatPT = [];
  bool isGridView = false;

  @override
  void initState() {
    super.initState();
    _loadData();
  }

  _loadData() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      kodePT = prefs.getStringList('kodePT') ?? [];
      namaPT = prefs.getStringList('namaPT') ?? [];
      alamatPT = prefs.getStringList('alamatPT') ?? [];
    });
  }

  _deleteData(int index) async {
    bool confirmDelete = await _showDeleteConfirmationDialog();
    if (confirmDelete) {
      SharedPreferences prefs = await SharedPreferences.getInstance();
      setState(() {
        kodePT.removeAt(index);
        namaPT.removeAt(index);
        alamatPT.removeAt(index);
      });
      await prefs.setStringList('kodePT', kodePT);
      await prefs.setStringList('namaPT', namaPT);
      await prefs.setStringList('alamatPT', alamatPT);
    }
  }

  Future<bool> _showDeleteConfirmationDialog() async {
    return await showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('Konfirmasi Hapus'),
          content: Text('Apakah Anda yakin ingin menghapus data ini?'),
          actions: [
            TextButton(
              child: Text('Batal'),
              onPressed: () {
                Navigator.of(context).pop(false);
              },
            ),
            TextButton(
              child: Text('Hapus'),
              onPressed: () {
                Navigator.of(context).pop(true);
              },
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Data Perguruan Tinggi'),
        backgroundColor: Colors.blueAccent,
        actions: [
          IconButton(
            icon: Icon(isGridView ? Icons.list : Icons.grid_view),
            onPressed: () {
              setState(() {
                isGridView = !isGridView;
              });
            },
          )
        ],
      ),
      body: kodePT.isEmpty
          ? Center(
              child: Text(
                'Belum ada data. Silakan tambahkan data baru.',
                style: TextStyle(fontSize: 18),
              ),
            )
          : isGridView
              ? GridViewPage(kodePT: kodePT, namaPT: namaPT, alamatPT: alamatPT)
              : ListViewPage(
                  kodePT: kodePT,
                  namaPT: namaPT,
                  alamatPT: alamatPT,
                  onEdit: (index) async {
                    final updated = await Navigator.push(
                      context,
                      MaterialPageRoute(
                        builder: (context) => FormPage(
                          index: index,
                          kodePT: kodePT[index],
                          namaPT: namaPT[index],
                          alamatPT: alamatPT[index],
                        ),
                      ),
                    );
                    if (updated != null) _loadData();
                  },
                  onDelete: _deleteData,
                ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () async {
          final added = await Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => FormPage(),
            ),
          );
          if (added != null) _loadData();
        },
      ),
    );
  }
}

class GridViewPage extends StatelessWidget {
  final List<String> kodePT;
  final List<String> namaPT;
  final List<String> alamatPT;

  GridViewPage({
    required this.kodePT,
    required this.namaPT,
    required this.alamatPT,
  });

  @override
  Widget build(BuildContext context) {
    return GridView.builder(
      padding: EdgeInsets.all(8),
      itemCount: kodePT.length,
      gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 2,
        crossAxisSpacing: 10,
        mainAxisSpacing: 10,
      ),
      itemBuilder: (context, index) {
        return Card(
          elevation: 4,
          child: InkWell(
            onTap: () {},
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                CircleAvatar(
                  child: Text(kodePT[index][0].toUpperCase()),
                ),
                SizedBox(height: 10),
                Text(namaPT[index],
                    style:
                        TextStyle(fontWeight: FontWeight.bold, fontSize: 16)),
                Text(alamatPT[index]),
              ],
            ),
          ),
        );
      },
    );
  }
}

class ListViewPage extends StatelessWidget {
  final List<String> kodePT;
  final List<String> namaPT;
  final List<String> alamatPT;
  final Function(int) onEdit;
  final Function(int) onDelete;

  ListViewPage({
    required this.kodePT,
    required this.namaPT,
    required this.alamatPT,
    required this.onEdit,
    required this.onDelete,
  });

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      padding: EdgeInsets.all(8),
      itemCount: kodePT.length,
      itemBuilder: (context, index) {
        return Card(
          elevation: 4,
          margin: EdgeInsets.symmetric(vertical: 8),
          child: InkWell(
            onTap: () {},
            child: ListTile(
              leading: CircleAvatar(
                child: Text(kodePT[index][0].toUpperCase()),
              ),
              title: Text(namaPT[index]),
              subtitle: Text(alamatPT[index]),
              trailing: Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  IconButton(
                    icon: Icon(Icons.edit, color: Colors.green),
                    onPressed: () => onEdit(index),
                  ),
                  IconButton(
                    icon: Icon(Icons.delete, color: Colors.red),
                    onPressed: () => onDelete(index),
                  ),
                ],
              ),
            ),
          ),
        );
      },
    );
  }
}

// Halaman input dan edit digabung
class FormPage extends StatefulWidget {
  final int? index;
  final String? kodePT;
  final String? namaPT;
  final String? alamatPT;

  FormPage({this.index, this.kodePT, this.namaPT, this.alamatPT});

  @override
  _FormPageState createState() => _FormPageState();
}

class _FormPageState extends State<FormPage> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _kodePTController;
  late TextEditingController _namaPTController;
  late TextEditingController _alamatPTController;

  @override
  void initState() {
    super.initState();
    _kodePTController = TextEditingController(text: widget.kodePT ?? '');
    _namaPTController = TextEditingController(text: widget.namaPT ?? '');
    _alamatPTController = TextEditingController(text: widget.alamatPT ?? '');
  }

  _saveOrUpdateData() async {
    if (_formKey.currentState!.validate()) {
      SharedPreferences prefs = await SharedPreferences.getInstance();
      List<String> kodePT = prefs.getStringList('kodePT') ?? [];
      List<String> namaPT = prefs.getStringList('namaPT') ?? [];
      List<String> alamatPT = prefs.getStringList('alamatPT') ?? [];

      if (widget.index == null) {
        // Add new data
        kodePT.add(_kodePTController.text);
        namaPT.add(_namaPTController.text);
        alamatPT.add(_alamatPTController.text);
      } else {
        // Update existing data
        kodePT[widget.index!] = _kodePTController.text;
        namaPT[widget.index!] = _namaPTController.text;
        alamatPT[widget.index!] = _alamatPTController.text;
      }

      await prefs.setStringList('kodePT', kodePT);
      await prefs.setStringList('namaPT', namaPT);
      await prefs.setStringList('alamatPT', alamatPT);

      Navigator.pop(context, true); // Berhasil disimpan atau diupdate
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.index == null
            ? 'Tambah Data Perguruan Tinggi'
            : 'Edit Data Perguruan Tinggi'),
        backgroundColor:
            widget.index == null ? Colors.blueAccent : Colors.green,
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Form(
          key: _formKey,
          child: Column(
            children: [
              TextFormField(
                controller: _kodePTController,
                decoration: InputDecoration(
                  labelText: 'Kode Perguruan Tinggi',
                  border: OutlineInputBorder(),
                ),
                validator: (value) =>
                    value!.isEmpty ? 'Kode tidak boleh kosong' : null,
              ),
              SizedBox(height: 16),
              TextFormField(
                controller: _namaPTController,
                decoration: InputDecoration(
                  labelText: 'Nama Perguruan Tinggi',
                  border: OutlineInputBorder(),
                ),
                validator: (value) =>
                    value!.isEmpty ? 'Nama tidak boleh kosong' : null,
              ),
              SizedBox(height: 16),
              TextFormField(
                controller: _alamatPTController,
                decoration: InputDecoration(
                  labelText: 'Alamat Perguruan Tinggi',
                  border: OutlineInputBorder(),
                ),
                validator: (value) =>
                    value!.isEmpty ? 'Alamat tidak boleh kosong' : null,
              ),
              SizedBox(height: 16),
              ElevatedButton(
                onPressed: _saveOrUpdateData,
                child: Text(widget.index == null ? 'Simpan' : 'Update'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}