Java 如何使用FirebaseAuth解决此问题？

我想使用firebaseAuth注册一个新用户，但不断出现错误

我已经使用invalidate和restart进行了调试，并重建了项目，甚至清理了项目，但它不会成功运行

注册活动

public class RegisterActivity extends AppCompatActivity{

private EditText mNickname;
private EditText mEmail;
private EditText mPassword;
private TextView gotoLoginPage;
private Button mRegisterbutton;
private FirebaseAuth mAuth;
private ProgressDialog mRegProgress;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_register);
    mNickname = findViewById(R.id.registerNicknameId);
    mEmail = findViewById(R.id.registerEmailId);
    mPassword = findViewById(R.id.registerPasswordId);
    FirebaseApp.initializeApp(this);


    mRegisterbutton = findViewById(R.id.registerButton);
    gotoLoginPage = findViewById(R.id.gotoLoginPage);

   getSupportActionBar().setTitle("Create new account");
   getSupportActionBar().setDisplayHomeAsUpEnabled(true);

   mRegProgress = new ProgressDialog(this);

    mRegisterbutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String nickname = mNickname.getText().toString();
            String email = mEmail.getText().toString();
            String password = mPassword.getText().toString();

            if (mNickname.equals("")|| mEmail.equals("") || mPassword.equals("")){
                Toast.makeText(getApplicationContext(), "Fill in the fields", Toast.LENGTH_LONG).show();
                mRegProgress.show();

                registerUser(email, password);
            }
            Intent toHomePage = new Intent(RegisterActivity.this, HomeActivity.class);
            startActivity(toHomePage);
            finish();
        }
    });

    gotoLoginPage.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent tologinPage = new Intent(RegisterActivity.this, LoginActivity.class);
            startActivity(tologinPage);
        }
    });

}

private void registerUser(String email, String password) {
    mAuth.createUserWithEmailAndPassword(email, password).addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            if (task.isSuccessful()){
                Intent gotoHomePage = new Intent(RegisterActivity.this, HomeActivity.class);
                startActivity(gotoHomePage);
                finish();
            }
        }
    });
}

}

这是我运行程序时遇到的错误。尝试在空对象引用上调用虚拟方法“com.google.firebase.auth.FirebaseUser com.google.firebase.auth.FirebaseAuth.getCurrentUser”

错误来自：

public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}

由于您没有初始化mAuth anywhere，因此这是null.getCurrentUser，它会抛出您得到的错误

在onCreate中初始化mAuth：

---

或者在使用它的地方用FirebaseAuth.getInstance替换mAuth。

糟糕的标题。在写你的题目和问题的主体时要非常具体。

public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}

mAuth = FirebaseAuth.getInstance();