I have a simple android application in which I am using Firebase Realtime Database to store the details of the signed in User.

Here is the User object that I am storing in the database:

public class User {

    private UserType userType;
    private String phoneNumber;
    private String fullName;
    private String email;

    // addresses are stored as HOSTEL.ROOMNUMBER format
    private String hostelAddress;

    public User(UserType userType, String phoneNumber, String fullName, String email, String hostelAddress) {
        this.userType = userType;
        this.phoneNumber = phoneNumber;
        this.fullName = fullName;
        this.email = email;
        this.hostelAddress = hostelAddress;
    }


    // required for realtime Database
    public User() {
    }

    // getters and setters for all fields...
}

Everytime A user signs in successfully (verified by Firebase Auth), I create a User object and store it as a value against the UID of the user as a key in the database. Everything upto this part works as expected.

Here is what that looks like:

{
  "users": {
    "<UID>": {
      "email": "<email>",
      "fullName": "<full name>",
      "hostelAddress": "<address>",
      "phoneNumber": "<number>",
      "userType": "CUSTOMER"
    }
  }
}

Now, I want to have a User Object, stored locally, that is synced with the User object stored in the database that corresponds to the currently signed user.
I want to access this User Object in different activities of my app.

For this I have made a separate class to interact with the database:

abstract public class FirebaseUtil {

    public static FirebaseDatabase database;

    public static User currentUserObject;

    public static String getCurrentUserID()
    {
        return FirebaseAuth.getInstance().getUid();
    }

    public static DatabaseReference getCurrentUserReference()
    {
        return database.getReference("users").child(getCurrentUserID());
    }

    static
    {

        database = FirebaseDatabase.getInstance();
        fetchCurrentUser();

    }
     
    public static void fetchCurrentUser()
    {
        if (getCurrentUserID()==null)
        {
            return;
        }
        getCurrentUserReference().addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {

                currentUserObject = snapshot.getValue(User.class);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
    }
   
   
    // Store user inside database, with the key as its UID.
    public static void storeUser(User user, String UID)
    {
        database.getReference("users").child(UID).setValue(user).addOnCompleteListener(new OnCompleteListener<Void>() {
            @Override
            public void onComplete(@NonNull Task<Void> task) {
                fetchCurrentUser();
            }
        });
    }
}

The problem is that this approach does not work, whenever I try to use the currentUserObject in another class in the app, its always null, even though the getCurrentUserID() method successfully returns the logged in User UID.

I haven’t tried many things since I have no idea at all why this could not be working.
I will appreciate any push in the right direction.

And if there is a better, more reliable way to achieve this task, please let me know.