Android - can't retrieve data from firebase wi

Question

My Firebase database structure is:

I want to retrieve the full name of some user, when I have its key.

My code:

public class ProfileActivity extends AppCompatActivity implements View.OnClickListener {

    private FirebaseAuth firebaseAuth;
    private TextView textView;
    private Button logbutton,wantToDeliverButton,lookForButton;
    private String userName;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_profile);
        Firebase.setAndroidContext(this);textView = (TextView)findViewById(R.id.textView2);
        Firebase usersRef = new Firebase("https://myfirstfirebaseauth.firebaseio.com");
        firebaseAuth = FirebaseAuth.getInstance();
        if (firebaseAuth.getCurrentUser() == null){
            finish();
            startActivity(new Intent(this,LoginActivity.class));
        }
        FirebaseUser user = firebaseAuth.getCurrentUser();
        Firebase ref = usersRef.child("User").child(user.getUid());
        ref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                userName = dataSnapshot.getValue(User.class).getFullName();

            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {

            }
        });
        textView.setText("welcome "+userName);
    }
}

But it set the textView to null. I try to put Toast inside the onDataChange() method, but it doesn't work. It seems it doesn't even get inside the method.

The line FirebaseUser user = firebaseAuth.getCurrentUser(); is correct because if i'm writing textView.setText("welcome "+ user.getEmail()); - I really get the correct email.

How to solve this? Am I using the correct listener? I don't want to change anything in the database, just retrieve.

Edit: it goes to onCancelled().

Answer 1

You're mixing capabilities from the legacy 2.5.X Firebase SDK (Example: Firebase.setAndroidContext()) and the new 9.X.X SDK (Example: FirebaseAuth.getInstance()). That is almost certainly a recipe for failure. Rework your code to use only the new SDK. The Setup Guide is here.