Ich mache eine Android-Anwendung. Ich logge den Benutzer zuerst mit E-Mail und Passwort ein und versuche dann in der OnComplete-Methode, wenn die Aufgabe erfolgreich ist, auf Daten in der Datenbank zuzugreifen. Aber jedes Mal, wenn ich die Nachricht "Listen at / failed" erhalte.

Mein Hauptaktivitätscode lautet wie folgt -

private FirebaseAuth auth;
private EditText inputEmail, inputPassword;
private Button btnLogin;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Firebase.setAndroidContext(this);
    //Get Firebase auth instance
    auth = FirebaseAuth.getInstance();

    if (auth.getCurrentUser() != null) {
        startActivity(new Intent(MainActivity.this, MainActivity.class));
        finish();
    }

    setContentView(R.layout.activity_main);
    inputEmail = (EditText) findViewById(R.id.txtMobile);
    inputPassword = (EditText) findViewById(R.id.txtPassword);
    btnLogin = (Button) findViewById(R.id.btnLogin);

    auth = FirebaseAuth.getInstance();


    btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String email = inputEmail.getText().toString();
            final String password = inputPassword.getText().toString();


            //authenticate user
            auth.signInWithEmailAndPassword(email, password)
                    .addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            // If sign in fails, display a message to the user. If sign in succeeds
                            // the auth state listener will be notified and logic to handle the
                            // signed in user can be handled in the listener.
                            if (!task.isSuccessful()) {
                                // there was an error
                                Log.e("Invalid","Invalid");

                            } else {
                                /*Intent intent = new Intent(MainActivity.this, Second.class);
                                startActivity(intent);
                                finish();*/
                                Firebase.getDefaultConfig();

                                auth = FirebaseAuth.getInstance();

                                if (auth.getCurrentUser() != null) {
                                    Log.e("awesome",auth.getCurrentUser().getEmail());
                                }

                                Firebase firebase = new Firebase("https://test-fd3f2.firebaseio.com");
                                firebase.addChildEventListener(new ChildEventListener() {
                                    // Retrieve new posts as they are added to Firebase
                                    @SuppressWarnings("unchecked")
                                    @Override
                                    public void onChildAdded(DataSnapshot snapshot, String previousChildKey) {
                                        if(snapshot.getValue()!= null) {
                                            String mobileNum = snapshot.getValue().toString();
                                            Log.e("here", mobileNum);
                                        }
                                        //Log.e("Title: ",newPost.get("password").toString());
                                    }

                                    @Override
                                    public void onChildChanged(DataSnapshot dataSnapshot, String s) {

                                    }

                                    @Override
                                    public void onChildRemoved(DataSnapshot dataSnapshot) {

                                    }

                                    @Override
                                    public void onChildMoved(DataSnapshot dataSnapshot, String s) {

                                    }

                                    @Override
                                    public void onCancelled(FirebaseError firebaseError) {
                                        Log.e("Cancel",firebaseError.getCode()+"");
                                        Log.e("Cancel",firebaseError.getDetails());
                                        Log.e("Cancel",firebaseError.getMessage());
                                    }
                                    //... ChildEventListener also defines onChildChanged, onChildRemoved,
                                    //    onChildMoved and onCanceled, covered in later sections.
                                });
                            }
                        }
                    });
        }
    });


}

UPDATE - Meine Firebase-Regeln lauten wie folgt:

        {
         "rules": {
         ".read": "auth != null",
         ".write": "auth != null"
          }
         }