使用FirebaseAuthListener，如果没有用户登录，它将导航到带有片段的活动

Question

What I am trying to do here is when I launch my MainActivity with FirebaseAuthListener and there is no user logged in it will navigate to the MainFragment and the MainFragment is for the container that connects to my SignInFragment (this SignInFragment is extended Fragment). So basically, the MainFragment is extended to AppCompatActivity .

It actually works all but my problem is the MainFragemnt is blank in my emulator, it supposed to be display the LoginFragment .

Here are my codes: MainActivity class

//Firebase
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;

private TextView mWelcome;
private Context mContext;

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

    mWelcome = findViewById(R.id.tvWelcome);

    setupFirebaseAuth();


}

/*
--------------------------------------Firebase-----------------------------------------
 */

private void getCurrentUser(FirebaseUser user){
    Log.d(TAG, "getCurrentUser: checking if user is logged in.");
    if (user == null){

        Intent intent = new Intent(this, MainFragment.class);
        startActivity(intent);
    }
}

private void setupFirebaseAuth(){
    Log.d(TAG, "setupFirebaseAuth: setting up firebase auth.");
    mAuth = FirebaseAuth.getInstance();
    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            //Check if the user is logged in
            FirebaseUser user = firebaseAuth.getCurrentUser();
            getCurrentUser(user);

            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");
            }
        }
    };
}

@Override
protected void onStart() {
    super.onStart();
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
protected void onStop() {
    super.onStop();
    if (mAuthListener != null){
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

My codes for MainFragment :

public class MainFragment extends AppCompatActivity {

@Override
public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
    super.onCreate(savedInstanceState, persistentState);
    setContentView(R.layout.fragment_main);

    SignInFragment fragment = new SignInFragment();

    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(R.id.container, fragment, null).commit();

My code for SignInFragment :

public class SignInFragment extends Fragment {

private static final String TAG = "SignInFragment";

private TextView mEmail, mPassword, mForRegister;
private EditText eEmail, ePassword;
private Button btnLogin;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.signin_fragment,container,false);

    //TextView
    mEmail = view.findViewById(R.id.tvEmail);
    mPassword = view.findViewById(R.id.tvPassword);
    mForRegister = view.findViewById(R.id.tvForRegister);
    //EditText
    eEmail = view.findViewById(R.id.etEmail);
    ePassword = view.findViewById(R.id.etPassword);
    //Button
    btnLogin = view.findViewById(R.id.btnLogin);

    //Navigating to RegisterFragment
    mForRegister.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            FragmentTransaction fr = getFragmentManager().beginTransaction();
            fr.replace(R.id.container, new RegisterFragment());
            fr.commit();
        }
    });

    return view;
}

This is the picture of the emulator:

Thank you!

Answer 1

try changing your onCreate method. use the following instead:

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