dart-我需要使用全局变量（颤振）访问函数中的变量

我已将一个变量声明为全局变量，需要使用此全局变量访问函数中的值。

我试过很多方法，但都不管用。

这怎么可能？
检查下面的代码

import 'package:flutter/material.dart';
import 'package:flutter/src/foundation/key.dart';
import 'package:flutter/src/widgets/framework.dart';
import 'package:shared_preferences/shared_preferences.dart';

class LoginScreen extends StatelessWidget {
  LoginScreen({Key? key}) : super(key: key);

  @override
  final inputtext = TextEditingController();
  String? value1;
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
          child: Center(
        child: Container(
          width: 300,
          child: Column(children: [
            TextField(
              controller: inputtext,
              decoration: InputDecoration(
                  border: OutlineInputBorder(), label: Text('Enter your name')),
            ),
            ElevatedButton.icon(
                onPressed: () {
                  savedata(context);
                  // print(value1);
                },
                icon: Icon(Icons.arrow_right),
                label: Text('click Here'))
          ]),
        ),
      )),
    );
  }

  Future savedata(BuildContext context) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setString('Name', inputtext.text);
    final savedValue = prefs.getString('Name');

    print(savedValue);
    // value1=savedValue.toString();
    if (savedValue == 'jibi') {
      Navigator.of(context).pushNamed('Screen_2');
      // print('Working');
    }
    this.value1 = savedValue;
  }
}