GridView json Img

Boa noite pessoal sou iniciante android e me deparei com o seguinte problema nao tou conseguindo carrega uma imagem dentro de uma gridview pelo json segue o code abaixo desde ja agradeco.

package beta.play.anime.animeplay;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.util.Log;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.GridView;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;

public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {

 private String TAG = MainActivity.class.getSimpleName();
 private ProgressDialog pDialog;
 private GridView lv;

 private static String url = "https://api.animeplay.app/?acao=ultimosepisodios";
 ArrayList<HashMap<String, String>> EpisodiosList;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 EpisodiosList = new ArrayList<>();

 lv = (GridView) findViewById(R.id.list);
 new GetUltimosEpisodios().execute();
 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) {
 Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
 .setAction("Action", null).show();
 }
 });

 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.addDrawerListener(toggle);
 toggle.syncState();

 NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
 navigationView.setNavigationItemSelectedListener(this);
 }
 private class GetUltimosEpisodios extends AsyncTask<Void, Void, Void> {

 @Override
 protected void onPreExecute() {
 super.onPreExecute();
 // Showing progress dialog
 pDialog = new ProgressDialog(MainActivity.this);
 pDialog.setMessage("Carregando Ultimos Episodios...");
 pDialog.setCancelable(false);
 pDialog.show();

 }
 @Override
 protected Void doInBackground(Void... arg0) {
 HttpHandler sh = new HttpHandler();

 // Making a request to url and getting response
 String jsonStr = sh.makeServiceCall(url);

 Log.e(TAG, "Response from url: " + jsonStr);

 if (jsonStr != null) {
 try {
 JSONObject jsonObj = new JSONObject(jsonStr);

 // Getting JSON Array node
 JSONArray episodios = jsonObj.getJSONArray("episodios");

 // looping through All episodios
 for (int i = 0; i < episodios.length(); i++) {
 JSONObject c = episodios.getJSONObject(i);

 String id = c.getString("id");
 String titulo = c.getString("titulo");
 String anime = c.getString("anime");
 String thumbnail = c.getString("thumbnail");
 String categoria = c.getString("categoria");

 // tmp hash map for single contact
 HashMap<String, String> episodio = new HashMap<>();

 // adding each child node to HashMap key => value
 episodio.put("id", id);
 episodio.put("titulo", titulo);
 episodio.put("anime", anime);
 episodio.put("thumbnail", thumbnail);

 // adding contact to contact list
 EpisodiosList.add(episodio);
 }
 } catch (final JSONException e) {
 Log.e(TAG, "Json parsing error: " + e.getMessage());
 runOnUiThread(new Runnable() {
 @Override
 public void run() {
 Toast.makeText(getApplicationContext(),
 "Json parsing error: " + e.getMessage(),
 Toast.LENGTH_LONG)
 .show();
 }
 });

 }
 } else {
 Log.e(TAG, "Couldn't get json from server.");
 runOnUiThread(new Runnable() {
 @Override
 public void run() {
 Toast.makeText(getApplicationContext(),
 "Couldn't get json from server. Check LogCat for possible errors!",
 Toast.LENGTH_LONG)
 .show();
 }
 });

 }

 return null;
 }
 @Override
 protected void onPostExecute(Void result) {
 super.onPostExecute(result);
 // Dismiss the progress dialog
 if (pDialog.isShowing())
 pDialog.dismiss();

 ListAdapter adapter = new SimpleAdapter(
 MainActivity.this, EpisodiosList,
 R.layout.list_item, new String[]{"titulo", "anime",
 "thumbnail"}, new int[]{R.id.titulo,
 R.id.anime, R.id.thumbnail});

 lv.setAdapter(adapter);
 }

 }

 @Override
 public void onBackPressed() {
 DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
 if (drawer.isDrawerOpen(GravityCompat.START)) {
 drawer.closeDrawer(GravityCompat.START);
 } else {
 super.onBackPressed();
 }
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu; this adds items to the action bar if it is present.
 getMenuInflater().inflate(R.menu.main, menu);
 return true;
 }

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
 // Handle action bar item clicks here. The action bar will
 // automatically handle clicks on the Home/Up button, so long
 // as you specify a parent activity in AndroidManifest.xml.
 int id = item.getItemId();

 //noinspection SimplifiableIfStatement
 if (id == R.id.action_settings) {
 return true;
 }

 return super.onOptionsItemSelected(item);
 }

 @SuppressWarnings("StatementWithEmptyBody")
 @Override
 public boolean onNavigationItemSelected(MenuItem item) {
 // Handle navigation view item clicks here.
 int id = item.getItemId();

 if (id == R.id.nav_camera) {
 // Handle the camera action
 } else if (id == R.id.nav_gallery) {

 } else if (id == R.id.nav_slideshow) {

 } else if (id == R.id.nav_manage) {

 } else if (id == R.id.nav_share) {

 } else if (id == R.id.nav_send) {

 }

 DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
 drawer.closeDrawer(GravityCompat.START);
 return true;
 }
}