How am i suppose to syncocnize this function? the main idea is to wait until every Request from firebase is finished

Question

The following Java code retrieves clothes data from a Firebase database. However, the Log.d(tag, "moved") and Log.d(tag, "signed in") lines don't print any messages and the main Activity is frozen.

public ArrayList<Clothe> getAllClothes() throws InterruptedException {
    synchronized (ClotheFirebaseHelper.this) {
        mAuth.signInWithEmailAndPassword("#########@gmail.com","**************").addOnCompleteListener(new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                ClotheFirebaseHelper.this.notifyAll();
                Log.d("tag","signed in");
            }
        });
        ClotheFirebaseHelper.this.wait();
    }
    Log.d("tag","moved");
    String uid = Objects.requireNonNull(mAuth.getCurrentUser()).getUid();
    Task<DataSnapshot> task = reference.child(uid).get();
    synchronized (ClotheFirebaseHelper.this) {
        task.onSuccessTask(new SuccessContinuation<DataSnapshot, Object>() {
            @NonNull
            @Override
            public Task<Object> then(DataSnapshot dataSnapshot) throws Exception {
                ClotheFirebaseHelper.this.notifyAll();
                return null;
            }
        });
        ClotheFirebaseHelper.this.wait();
    }
    Log.d("tag","ready?");
    Log.d("tag",task.getResult().toString());
    return null;
}