title: cannot resolve symbol okhttp
body: <p>i am developing a gcm chat app in android studio and i am getting this error n no idea how to resolve it. i searched about it but didn't find any thing.
  Here is the code and in MainActivity.java also having same problem. </p>
  
  <pre><code>package com.example.jason.androidchat2;
  import android.app.Activity;
  import android.content.BroadcastReceiver;
  import android.content.Context;
  import android.content.Intent;
  import android.content.IntentFilter;
  import android.os.AsyncTask;
  import android.support.annotation.NonNull;
  import android.support.v4.content.LocalBroadcastManager;
  import android.support.v7.app.ActionBarActivity;
  import android.os.Bundle;
  import android.util.Log;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.View;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.ListView;
  import android.widget.Toast;
  import com.squareup.okhttp.OkHttpClient;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.HttpURLConnection;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.util.ListIterator;
  
  
  public class ChatActivity extends Activity {
  
  EditText editText_mail_id;
  EditText editText_chat_message;
  ListView listView_chat_messages;
  Button button_send_chat;
  List&lt;ChatObject&gt; chat_list;
  
  BroadcastReceiver recieve_chat;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_chat);
  
      editText_mail_id= (EditText) findViewById(R.id.editText_mail_id);
      editText_chat_message= (EditText)       findViewById(R.id.editText_chat_message);
      listView_chat_messages= (ListView) findViewById(R.id.listView_chat_messages);
      button_send_chat= (Button) findViewById(R.id.button_send_chat);
      button_send_chat.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
  
              // send chat message to server
              String message=editText_chat_message.getText().toString();
  
              showChat("sent",message);
  
              new SendMessage().execute();
  
              editText_chat_message.setText("");
  
  
          }
      });
  
  
      recieve_chat=new BroadcastReceiver() {
          @Override
          public void onReceive(Context context, Intent intent) {
  
              String message=intent.getStringExtra("message");
  
              Log.d("pavan","in local braod "+message);
              showChat("recieve",message);
  
  
          }
      };
  
      LocalBroadcastManager.getInstance(this).registerReceiver(recieve_chat, new IntentFilter("message_recieved"));
  
  
  
  }
  
  private void showChat(String type, String message){
  
      if(chat_list==null || chat_list.size()==0){
  
          chat_list= new ArrayList&lt;ChatObject&gt;();
      }
  
      chat_list.add(new ChatObject(message,type));
  
      ChatAdabter chatAdabter=new ChatAdabter(ChatActivity.this,R.layout.chat_view,chat_list);
  
      listView_chat_messages.setAdapter(chatAdabter);
      //chatAdabter.notifyDataSetChanged();
  
  }
  
  
  @Override
  protected void onDestroy() {
      super.onDestroy();
  
  }
  
  private class SendMessage extends AsyncTask&lt;String, Void, String&gt; {
  
      @Override
      protected void onPreExecute() {
          // TODO Auto-generated method stub
          super.onPreExecute();
      }
  
      @Override
      protected String doInBackground(String... params) {
          // TODO Auto-generated method stub
  
          String url = Util.send_chat_url+"?email_id="+editText_mail_id.getText().toString()+"&amp;message="+editText_chat_message.getText().toString();
          Log.i("pavan", "url" + url);
  
          OkHttpClient client_for_getMyFriends = new OkHttpClient();;
  
          String response = null;
          // String response=Utility.callhttpRequest(url);
  
          try {
              url = url.replace(" ", "%20");
              response = callOkHttpRequest(new URL(url),
                      client_for_getMyFriends);
              for (String subString : response.split("&lt;script", 2)) {
                  response = subString;
                  break;
              }
          } catch (MalformedURLException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          } catch (IOException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
  
  
          return response;
      }
  
      @Override
      protected void onPostExecute(String result) {
          // TODO Auto-generated method stub
          super.onPostExecute(result);
          //Toast.makeText(context,"response "+result,Toast.LENGTH_LONG).show();
  
      }
  
  
  }
  
  // Http request using OkHttpClient
  String callOkHttpRequest(URL url, OkHttpClient tempClient)
          throws IOException {
  
      HttpURLConnection connection = tempClient.open(url);
  
      connection.setConnectTimeout(40000);
      InputStream in = null;
      try {
          // Read the response.
          in = connection.getInputStream();
          byte[] response = readFully(in);
          return new String(response, "UTF-8");
      } finally {
          if (in != null)
              in.close();
      }
  }
  
  byte[] readFully(InputStream in) throws IOException {
      ByteArrayOutputStream out = new ByteArrayOutputStream();
      byte[] buffer = new byte[1024];
      for (int count; (count = in.read(buffer)) != -1;) {
          out.write(buffer, 0, count);
      }
      return out.toByteArray();
  }
  </code></pre>
  
  <p>}</p>