Shared Preference

 import "package:flutter/material.dart";

import "package:shared_preferences/shared_preferences.dart";

void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  MyApp({super.key}) : super();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: "shared Preferences",
      theme: ThemeData(
        primarySwatch: Colors.grey,
      ),
      home: DemoShare(),
    );
  }
}
class DemoShare extends StatefulWidget {
  DemoShare({super.key}) : super();

  @override
  State<DemoShare> createState() => _DemoShareState();
}

class _DemoShareState extends State<DemoShare> {
  var nameController = TextEditingController();

  static const String KEYNAME = "name";
  var nameValue = "No value saved";

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Shared Preferences"),
      ),
      body: Container(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Padding(
              padding: const EdgeInsets.all(40.0),
              child: TextField(
                controller: nameController,
                decoration: InputDecoration(
                  hintText: "Name",
                  labelText: "Name",
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(11.0,),
                    borderSide: BorderSide(
                      width: 2.0,
                      color: Colors.brown,
                    ),
                  ),
                  enabledBorder: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(11.0,),
                    borderSide: BorderSide(
                      width: 2.0,
                      color: Colors.blue,
                    ),
                  ),
                ),
              ),
            ),
            ElevatedButton(
              onPressed: () async {
                var name = nameController.text.toString();

                var prefs = await SharedPreferences.getInstance();

                prefs.setString(KEYNAME, name);
              },
              child: Text("Save"),
            ),
            SizedBox(height: 30.0,),
            Text(nameValue),
          ],
        ),
      ),
    );
  }
  void getValue() async {
    var prefs = await SharedPreferences.getInstance();

    var getName = prefs.getString(KEYNAME);

    setState(() {
      nameValue = getName != null ? getName : "No Saved Value";   //OR below
      //nameValue = getName ?? "No Saved Value";
    },);
  }
}