Java.Lang.NullPointerException：尝试调用虚拟方法'void com.google.firebase.auth.FirebaseAuth.zza

Question

我正在尝试按照 Xamarin Android 上的 Google official documentation 使用电话号码在 Android 上使用 Firebase 实现身份验证。但是我收到了这个错误：

Java.Lang.NullPointerException: 'Attempt to invoke virtual method 'void com.google.firebase.auth.FirebaseAuth.zza(java.lang.String, long, java.util.concurrent.TimeUnit, com.google.firebase.auth.PhoneAuthProvider$OnVerificationStateChangedCallbacks, android.app.Activity, java.util.concurrent.Executor, boolean)' on a null object reference'

我创建了一个 Android 工作室项目并且发送短信没有错误。我本来应该昨天发布应用程序的，但我被困在这里了。

注意：我已经引用了Xamarin.GooglePlayServices.Base、Xamarin.Firebase.Auth:71.1605.0，并且我有一个带有推送通知FCM 的代码，它工作正常。

这是我的MainActivity.OnCreate 代码：

        TabLayoutResource = Resource.Layout.Tabbar;
        ToolbarResource = Resource.Layout.Toolbar;

        base.OnCreate(savedInstanceState);

        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
        LoadApplication(new App());

        Xamarin.FormsMaps.Init(this, savedInstanceState);

        FirebaseApp firebaseApp = FirebaseApp.InitializeApp(this);

        var firebaseAuthInstance = FirebaseAuth.GetInstance(firebaseApp);

        if(firebaseAuthInstance == null)
        {
            firebaseAuthInstance = new FirebaseAuth(firebaseApp);
        }

        verificationStateChangedCallbacks = new VerificationStateChangedCallbacks(); //This class is below.

        PhoneAuthProvider.Instance.VerifyPhoneNumber("+16505559999", 60, TimeUnit.Seconds, this //The activity, verificationStateChangedCallbacks); // I got the error here

班级VerificationStateChangedCallbacks:

public class VerificationStateChangedCallbacks : OnVerificationStateChangedCallbacks
    {
        public override void OnVerificationCompleted(PhoneAuthCredential p0)
        {
        }

        public override void OnVerificationFailed(FirebaseException p0)
        {
        }

        public override void OnCodeSent(string p0, ForceResendingToken p1)
        {
            base.OnCodeSent(p0, p1);
        }
    }

Answer 1

我只是通过更改来修复它

PhoneAuthProvider.Instance.VerifyPhoneNumber("+16505559999", 60, TimeUnit.Seconds, this, verificationStateChangedCallbacks);

到

PhoneAuthProvider.GetInstance(firebaseAuthInstance).VerifyPhoneNumber("+16505559999", 60, TimeUnit.Seconds, this, verificationStateChangedCallbacks);

2 天，我没想过要换。

Answer 2

您能否检查“PhoneAuthProvider.Instance”是否为空对象。如果是，请检查您的文件“google-services.json”。通常“FirebaseAuth.GetInstance(firebaseApp)”不会返回 null。