@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_login, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

//        binding = DataBindingUtil.setContentView(getActivity(), R.layout.fragment_login);

//        binding = DataBindingUtil.bind(view);
//        binding.setLifecycleOwner(requireActivity());
//        binding.setViewModel(viewModel);

        viewModel = ViewModelProviders.of(getActivity()).get(GetViewModel.class);

        //입력한 값 얻어옴
        editTextEmail = getActivity().findViewById(R.id.editTextLEmail);
        editTextPwd = getActivity().findViewById(R.id.editTextLPwd);





        //로그인 버튼 클릭
        buttonOverlap = getActivity().findViewById(R.id.buttonOverlap);
        buttonOverlap.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //editText에 입력된 값을 가져옴
                final String user_id = editTextEmail.getText().toString().trim();
                final String user_pw = editTextPwd.getText().toString().trim();
                if(user_id.isEmpty() || user_pw.isEmpty()){
                    Toast.makeText(getActivity(), "아이디와 비밀번호를 입력해주세요.", Toast.LENGTH_SHORT).show();
                    return;
                }



                Response.Listener<String> responseListener = new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONObject jsonObject = new JSONObject(response);
                            boolean success = jsonObject.getBoolean("success"); //(jsp에서 성공하면 response["success"] = true; 해준것을 받아옴)
                            if (success) { //로그인에 성공한 경우
                                String user_id = jsonObject.getString("user_id"); //서버로부터 유저 아이디, 패스워드 받음
                                String user_pw = jsonObject.getString("user_pw");
//                                Toast.makeText(getActivity(), "로그인 되었습니다.", Toast.LENGTH_SHORT).show();
                                NavHostFragment.findNavController(LoginFragment.this).navigate(R.id.action_loginFragment_to_MailboxNoticeFragment);

                                viewModel.getID(user_id);
//                                Bundle bundle = new Bundle();
//                                bundle.putString("user_id", user_id);
//                                NavHostFragment.findNavController(LoginFragment.this).navigate(R.id.action_loginFragment_to_MailboxNoticeFragment, bundle);
                            } else{ //로그인에 실패한 경우
                                Toast.makeText(getActivity(), "아이디 또는 비밀번호를 확인해주세요.", Toast.LENGTH_SHORT).show();
                                return;
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                };
                LoginRequest loginRequest = new LoginRequest(user_id, user_pw, responseListener);
                RequestQueue queue = Volley.newRequestQueue(getActivity());
                queue.add(loginRequest);

            }
        });

        //회원가입 버튼 클릭
        buttonSignup = getActivity().findViewById(R.id.buttonSignup);
        buttonSignup.setOnClickListener( new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavHostFragment.findNavController(LoginFragment.this).navigate(R.id.action_loginFragment_to_signupFragment);
            }
        });


    }

    //앱바 죽이기
    @Override
    public void onResume() {
        super.onResume();

        ((MainActivity)getActivity()).getSupportActionBar().hide();
    }

}

        viewModel = ViewModelProviders.of(getActivity()).get(GetViewModel.class);
//        binding = DataBindingUtil.bind(view);
//        binding.setLifecycleOwner(requireActivity());
//        binding.setViewModel(viewModel);


        String id = viewModel.outID();

        Toast.makeText(getActivity(), id+"값",Toast.LENGTH_LONG);

import androidx.lifecycle.ViewModel;

public class GetViewModel extends ViewModel {
    public String user_id = "hi";

    public void getID(String id){
        user_id = id;
    }

    public String outID(){
        return user_id;
    }
}

<data> <variable name="ViewModel" type="androidx.lifecycle.ViewModel"/> </data>