onClickListener与onCompleteListener：无法解析addOnSuccessListener

Question

我要在登录之前验证用户输入的职业，因为在注册时已经输入了他们的职业。因此，我在validate(prof)内调用OnClickListener方法进行登录，然后在验证该职业之后，我将在OnSuccessListener内调用signing方法。

btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            progressBar.setVisibility(View.VISIBLE);
            //  btnLogin.setVisibility(View.INVISIBLE);

            final String email = userEmail.getText().toString();
            final String pass = userPass.getText().toString();

            if (email.isEmpty() || pass.isEmpty()) {
                showMessage("Please verify all fields");
                btnLogin.setVisibility(View.VISIBLE);
                progressBar.setVisibility(View.INVISIBLE);
            } else {
                String userId = mAuth.getUid();
                Log.d(TAG, "userid is: " + userId);
                validateprof(userId).addOnSuccessListener
                (new OnSuccessListener<Void>(){
                        @Override
                        public void onSuccess(Void aVoid) {}
                    });
                signIn(email, pass);
            }
        }
    });