Anonymous login is not triggering onAuthStateChanged callback

Question

I'm logging in my users anonymously if they are not logged in, but the onAuthStateChanged callback is not being triggered. Additionally, whenever I try to use mAuth.getCurrentUser().getUid() , it gives me a NullPointerException. Here is my code:

mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {

            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {

                FirebaseUser user = firebaseAuth.getCurrentUser();

                if (user != null) {

                    // do something

                } else {

                    mAuth.signInAnonymously().addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            System.out.println("SIGNED IN ANONYMOUSLY");
                            System.out.println(mAuth.getCurrentUser().getUid()); // crashes here
                        }
                    });

                }
            }
        };

Been stuck on this for hours and I have no idea what the issue could be.

Thanks in advance for any help.

Answer 1

I am pretty much sure its because your signInAnonymously call is not returning successful in onComplete callback. Replace

System.out.println("SIGNED IN ANONYMOUSLY");
System.out.println(mAuth.getCurrentUser().getUid());

with

if (task.isSuccessful()) {
    System.out.println("SIGNED IN ANONYMOUSLY");
    System.out.println(mAuth.getCurrentUser().getUid());
}
else{
    Log.i(TAG, "signInAnonymously", task.getException());
}

and check the exception