title: The method getActivity() is undefined for the type MainActivity
body: <p>I'm trying to use the demo how ever when I have pulled it in to my MainActivity I am getting the error "The method getActivity() is undefined for the type MainActivity"</p>
  
  <p>createRequestSuccessListener() and createRequestErrorListener() also got the same problem</p>
  
  <pre><code>package com.example.testgetanik;
  
      import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.HashMap;
  import java.util.Map;
  
  import com.android.volley.Request.Method;
  import com.android.volley.RequestQueue;
  import com.android.volley.toolbox.Volley;
  import android.os.Bundle;
  import android.app.Activity;
  import android.view.Menu;
  import com.android.volley.Response.ErrorListener;
  
  public class MainActivity extends Activity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          Map&lt;String, String&gt; params = new HashMap&lt;String, String&gt;();
          params.put("id","1");
          params.put("name", "myname");
  
          String url = "http://api.rottentomatoes.com/api/public/v1.0/movies/770672123/cast.json?apikey=3p9ehnhzbxwpbd6mk8fncf67";
          RequestQueue requestQueue = Volley.newRequestQueue(getActivity());
          CustomRequest jsObjRequest = new CustomRequest(Method.POST,url,params,this.createRequestSuccessListener(),this.createRequestErrorListener());
  
          requestQueue.add(jsObjRequest);
          try{
              URL urlToRequest = new URL(url);
              WebServiceAsyncTask asyncTask = new WebServiceAsyncTask();
              asyncTask.execute(urlToRequest);
          }catch(MalformedURLException e){
              e.printStackTrace();
          }
      }
  
      @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;
      }
  
  }
  </code></pre>