apinya
<?php
if($_SERVER['REQUEST_METHOD']=='POST'){
 $nip = $_POST['nip'];
 $password = $_POST['password'];
 $id_jabatan = $_POST['id_jabatan'];
  $sql = "select * from data_pegawai where nip='$nip' and password='$password' and id_jabatan ='$id_jabatan'";

require_once('dbConnect.php');
 $result = mysqli_query($con,$sql);
 $check = mysqli_fetch_array($result);
 if(isset($check)){
 $json['status'] = 200;
    echo json_encode($json);
 }else{
  $json['status'] = 400;
    echo json_encode($json);
 }
 }
 ?>

-----------------
oncreate
 spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                if (spin.getSelectedItemPosition() == 0){
                    Toast.makeText(getApplicationContext(),"harap pilih jabatan",Toast.LENGTH_LONG).show();
                } else  if (spin.getSelectedItemPosition() == 1){
                jabatan = "jbt1";
            } else  if (spin.getSelectedItemPosition() == 2){
                jabatan = "jbt2";
                } else  if (spin.getSelectedItemPosition() == 3){
                    jabatan = "jbt3";
                }
            }

restManager = new RestManager();
        mApiService = restManager.ambil_data_kegiatan();
        sharedPrefManager = new SharedPrefManager(this);

if (sharedPrefManager.getSPSudahLogin()){
            Intent in = new Intent(login.this, MainActivity.class);

            startActivity(in);
            finish();
        }

private void requestLogin(){
        mApiService.loginRequest(user.getText().toString(), pass.getText().toString(),jabatan)
                .enqueue(new Callback<ResponseBody>() {
                    @Override
                    public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
                        if (response.code() == 200){
                            loading.dismiss();
                                    Toast.makeText(mContext, "BERHASIL LOGIN", Toast.LENGTH_SHORT).show();
                                    sharedPrefManager.saveSPString(SharedPrefManager.SP_NAMA, user.getText().toString());
                                    sharedPrefManager.saveSPString(SharedPrefManager.SP_jab, jabatan);
                                    sharedPrefManager.saveSPBoolean(SharedPrefManager.SP_SUDAH_LOGIN, true);
                                    Intent in = new Intent(login.this, MainActivity.class);
                                    in.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
                                    startActivity(in);
                                    finish();
                                    Log.d("hasilnya ",response.message().toString());
                        } else if (response.code() == 400){
                            loading.dismiss();
                            response.message().toString();
                            Log.d("hasilnyacode ",response.message().toString());
                        }
                    }

                    @Override
                    public void onFailure(Call<ResponseBody> call, Throwable t) {
                        Log.e("debug", "onFailure: ERROR > " + t.toString());
                        loading.dismiss();
                        Log.d("hasilnya ",t.getMessage().toString());
                    }

---------------------------------------
 @FormUrlEncoded
    @POST("login.php")
    Call<ResponseBody> loginRequest(@Field("nip") String nip,
                                    @Field("password") String password, @Field("id_jabatan") String id_jabatan);

-----------------------------------
public class SharedPrefManager {

    public static final String SP_MAHASISWA_APP = "spMahasiswaApp";

    public static final String SP_NAMA = "spNama";
    public static final String SP_jab = "spjab";
    public static final String SP_EMAIL = "spEmail";
    public static final String SUCCESS = "success";
    public static final String FAILURE = "failure";

    public static final String SP_SUDAH_LOGIN = "spSudahLogin";

    SharedPreferences sp;
    SharedPreferences.Editor spEditor;

    public SharedPrefManager(Context context){
        sp = context.getSharedPreferences(SP_MAHASISWA_APP, Context.MODE_PRIVATE);
        spEditor = sp.edit();
    }

    public void saveSPString(String keySP, String value){
        spEditor.putString(keySP, value);
        spEditor.commit();
    }

    public void saveSPInt(String keySP, int value){
        spEditor.putInt(keySP, value);
        spEditor.commit();
    }

    public void saveSPBoolean(String keySP, boolean value){
        spEditor.putBoolean(keySP, value);
        spEditor.commit();
    }

    public String getSPNama(){
        return sp.getString(SP_NAMA, "");
    }

    public String getSP_jab(){
        return sp.getString(SP_jab, "");
    }

    public String getSPEmail(){
        return sp.getString(SP_EMAIL, "");
    }

    public Boolean getSPSudahLogin(){
        return sp.getBoolean(SP_SUDAH_LOGIN, false);
    }
}