Заполнение Recycleview, дающее ноль в JsonArrayRequest

У меня есть этот код, я пытаюсь получить JSON код из PHP сценарий с Android Studio, а затем получить URL-адрес изображения и имя, чтобы нарисовать RecycleView с некоторыми списками и заполнить его … я всегда получаю NullPointerException из JsonArrayRequest в JSON_DATA_WEB_CALL() метод, и моя голова взорвется, я не могу найти решение. PHP был также протестирован, и он работает, он отображает JSON правильно … любая помощь будет отличной. Спасибо заранее. Вот код:

getData.php

<?php

//importing Config file
include 'include/Config.php';

// Create connection
$conn = new mysqli(DB_HOST,DB_USER,DB_PASSWORD,DB_DATABASE);

if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

$sql ="SELECT * FROM imageplums";
$result = $conn->query($sql);

if ($result->num_rows >0) {
// output data of each row
while($row[] = $result->fetch_assoc()) {
$tem = $row;
$json = json_encode($tem);
}
} else {
echo "0 results";
}

echo $json;
$conn->close();
?>

MainActivity.Java

public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
public TextView text;
public static String MAIL_KEY;
RecyclerView recyclerView;
RecyclerView.Adapter pAdapter;
RecyclerView.LayoutManager recyclerViewlayoutManager;
List<PlumImage> plumList;

String GET_JSON_DATA_HTTP_URL = "http://192.168.1.39:8080/plumster/getdata.php";
String JSON_IMAGE_TITLE_NAME = "image_title";
String JSON_IMAGE_URL = "image_url";

JsonArrayRequest jsonArrayRequest ;
RequestQueue requestQueue ;

private SessionManager session;
private SQLiteHandler db;@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

plumList=new ArrayList<>();

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
addPlum();
}
});

DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();

NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view); //Creamos Navigationview que corresponde a nav_header_main.xml
navigationView.setNavigationItemSelectedListener(this);
View header=navigationView.getHeaderView(0);
text=(TextView)header.findViewById(R.id.textViewEmail);

// SqLite database handler
db = new SQLiteHandler(getApplicationContext());

// session manager
session = new SessionManager(getApplicationContext());// Fetching user details from sqlite
HashMap<String, String> user = db.getUserDetails();

MAIL_KEY = user.get("email");recyclerView=(RecyclerView) findViewById(R.id.recyclerview);
recyclerView.setHasFixedSize(true);
recyclerViewlayoutManager = new LinearLayoutManager(this);

recyclerView.setLayoutManager(recyclerViewlayoutManager);
//recyclerView.setLayoutManager(new GridLayoutManager(this,2));
JSON_DATA_WEB_CALL();

}public void JSON_DATA_WEB_CALL() {
//Showing a progress dialog
//final ProgressDialog loading = ProgressDialog.show(this, "Loading data", "Please wait...", false, false);

JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(GET_JSON_DATA_HTTP_URL,

new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {

JSON_PARSE_DATA_AFTER_WEBCALL(response);
//loading.dismiss();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {

Toast.makeText(getApplicationContext(),
error.networkResponse.toString(), Toast.LENGTH_LONG)
.show();
}
});

requestQueue = Volley.newRequestQueue(this);

requestQueue.add(jsonArrayRequest);
}

//This method will parse json data
public void JSON_PARSE_DATA_AFTER_WEBCALL(JSONArray array){

for(int i = 0; i<array.length(); i++) {

PlumImage plumImage = new PlumImage();

JSONObject json = null;
try {

json = array.getJSONObject(i);

plumImage.setName(json.getString(JSON_IMAGE_TITLE_NAME));

plumImage.setPhoto(json.getString(JSON_IMAGE_URL));

} catch (JSONException e) {

e.printStackTrace();
}
plumList.add(plumImage);
}

pAdapter = new PlumAdapter(plumList, this);

recyclerView.setAdapter(pAdapter);
}