在此过程中未初始化默认FirebaseApp

Question

我尝试使用Firebase创建身份验证活动，如下所示：

private TextView mStatusTextView;
private TextView mDetailTextView;
private EditText mEmailField;
private EditText mPasswordField;

private FirebaseAuth mAuth;

private FirebaseAuth.AuthStateListener mAuthListener;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_authentication);

    // Views
    mStatusTextView = (TextView) findViewById(R.id.status);
    mDetailTextView = (TextView) findViewById(R.id.detail);
    mEmailField = (EditText) findViewById(R.id.field_email);
    mPasswordField = (EditText) findViewById(R.id.field_password);

    // Buttons
    findViewById(R.id.email_sign_in_button).setOnClickListener(this);
    findViewById(R.id.email_create_account_button).setOnClickListener(this);
    findViewById(R.id.sign_out_button).setOnClickListener(this);

    mAuth = FirebaseAuth.getInstance();

    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                // User is signed in
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {
                // User is signed out
                Log.d(TAG, "onAuthStateChanged:signed_out");
            }
            updateUI(user);          
        }
    };      
}

但是我收到以下错误：

  

java.lang.RuntimeException：无法启动活动ComponentInfo {trakr.Authentication}：java.lang.IllegalStateException：默认FirebaseApp未在此进程trakr.kade_c.trakr中初始化。请务必先调用FirebaseApp.initializeApp（Context）。

即使我添加FirebaseApp.initializeApp(this)，也会抛出相同的异常。

请注意，我的MainActivity只是简单地调用我的Authentication课程：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    startActivity(new Intent(this, Authentication.class));
}