setListAdapter unable to be resolved

a real amateur developer here in dire need of some assistance. I've been trying to parse JSON data and turn it into a list of items, but I am having difficulties attempting to use the setListAdapter method despite importing it into the class. Any help would be massively appreciated.

Here is my main activity, error is in the onPostExecute method

import java.io.IOException;
import java.util.List;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;

import android.app.Activity;
import android.net.http.AndroidHttpClient;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;


public class JSON extends Activity {

    // Coordinates used for centering the Map

    private final static String UNAME = "aporter";
    private final static String URL = "http://api.geonames.org/earthquakesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&username="
            + UNAME;

    public static final String TAG = "MapsEarthquakeMapActivity";

    // Set up UI and get earthquake data
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        new HttpGetTask().execute(URL);

    }

    private class HttpGetTask extends
            AsyncTask<String, Void, List<GeonameRec>> {

        AndroidHttpClient mClient = AndroidHttpClient.newInstance("");

        @Override
        protected List<GeonameRec> doInBackground(String... params) {

            HttpGet request = new HttpGet(params[0]);
            JSONResponseHandler responseHandler = new JSONResponseHandler();

            try {

                // Get Earthquake data in JSON format
                // Parse data into a list of EarthQuakeRecs

                return mClient.execute(request, responseHandler);

            } catch (ClientProtocolException e) {
                Log.i(TAG, "ClientProtocolException");
            } catch (IOException e) {
                Log.i(TAG, "IOException");
            }

            return null;

        }

        @Override
        protected void onPostExecute(List<GeonameRec> result) {

            if (null != mClient)
                mClient.close();
            setListAdapter(new ArrayAdapter<String>(
                 JSON.this,
                 R.layout.listitem, result));



        }
    }

}
}

And here is my class where I format the JSON response.

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.impl.client.BasicResponseHandler;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONTokener;

public class JSONResponseHandler implements
    ResponseHandler<List<GeonameRec>> {
@Override
public List<GeonameRec> handleResponse(HttpResponse response)
        throws ClientProtocolException, IOException {
    List<GeonameRec> result = new ArrayList<GeonameRec>();
    String JSONResponse = new BasicResponseHandler()
            .handleResponse(response);
    try {
        JSONObject object = (JSONObject) new JSONTokener(JSONResponse)
                .nextValue();
        JSONArray earthquakes = object.getJSONArray("earthquakes");
        for (int i = 0; i < earthquakes.length(); i++) {
            JSONObject tmp = (JSONObject) earthquakes.get(i);
            result.add(new GeonameRec(
                    tmp.getDouble("lat"),
                    tmp.getDouble("lng")));
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return result;
}

}