我正在尝试使用 Dart Flutter 进行 Google Auth 操作。
我制作了与我观看的视频中完全相同的代码。虽然它没有在视频中给出错误,但它给了我一个错误。
我的代码:
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:google_sign_in/google_sign_in.dart';
class GoogleSignInProvider extends ChangeNotifier {
final googleSignIn = GoogleSignIn();
bool _isSigningIn;
GoogleSignInProvider() {
_isSigningIn = false;
}
bool get isSigningIn => _isSigningIn;
set isSigningIn(bool isSigningIn) {
_isSigningIn = isSigningIn;
notifyListeners();
}
Future login() async {
isSigningIn = true;
final user = await googleSignIn.signIn();
if (user == null) {
isSigningIn = false;
return;
} else {
final googleAuth = await user.authentication;
final credential = GoogleAuthProvider.credential(
accessToken: googleAuth.accessToken,
idToken: googleAuth.idToken,
);
await FirebaseAuth.instance.signInWithCredential(credential);
isSigningIn = false;
}
}
void logout() async {
await googleSignIn.disconnect();
FirebaseAuth.instance.signOut();
}
}
错误:
GoogleSignInProvider GoogleSignInProvider()
package:todolist/google_sign_in.dart
Non-nullable instance field '_isSigningIn' must be initialized.
Try adding an initializer expression, or add a field initializer in this constructor, or mark it 'late'.
问题是什么?我该如何解决?我提前感谢您的帮助。
最佳答案
因为您的值不可为空,所以它需要一个默认值
bool _isSigningIn; //non-nullable variable should be inialized
bool? _isSigningIn; //nullable variable and does not requires initialization
如果你让你的变量可以为空,你可以让它保持未初始化,在其他情况下,你应该在定义它时初始化它bool _isSigningIn = false;
或者在你的构造函数里面有一个值,像这样:GoogleSignInProvider(this._isSigningIn);
还有一个选项,你也可以给一个默认值:请参见下面的示例:
class GoogleSignInProvider extends ChangeNotifier {
final googleSignIn = GoogleSignIn();
bool _isSigningIn;
GoogleSignInProvider([this._isSigningIn = false]);
}
关于android - Dart Flutter "Non-nullable instance field ' _isSigningIn' 必须初始化。”错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/71578071/