Android : How to display multiple locations in google map in android

In my activity, I've added a google map. I'm retrieving multiple Location Name, Latitude and Longitude from mySql database to activity. Now, I want to display all these locations in a single map. For this, I've wrote following code :

package com.googlemaps;

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

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends Activity 
{
    private GoogleMap googleMap;
    String Latitude,Longitude,Location;
    MapView mapView;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
        googleMap.setMyLocationEnabled(true);
        RetriveLatLong();

        MarkerOptions marker=new MarkerOptions().position(new LatLng(Double.parseDouble(Latitude),
                Double.parseDouble(Longitude))).title(Location);
        googleMap.addMarker(marker);
        marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_BLUE));
        googleMap.getUiSettings().setAllGesturesEnabled(true);
    }

    /**
     * function to load map. If map is not created it will create it for you
     * */
    @SuppressLint("NewApi")
    private void initilizeMap() 
    {
        if (googleMap == null) 
        {
            googleMap=((MapFragment)getFragmentManager().findFragmentById(R.id.map)).getMap();

            // check if map is created successfully or not
            if (googleMap == null) {
                Toast.makeText(getApplicationContext(),
                        "Sorry! unable to create maps", Toast.LENGTH_SHORT).show();
            }
        }
    }

    @Override
    protected void onResume() 
    {
        super.onResume();
        initilizeMap();
    }


    private void RetriveLatLong() 
    {
        // TODO Auto-generated method stub
        String data;
        List<String> r = new ArrayList<String>();
        final List<String> r1 = new ArrayList<String>();
        List<String> r2 = new ArrayList<String>();
        List<Map<String, String>> data1 = new ArrayList<Map<String, String>>();

        try 
        {
                DefaultHttpClient client = new DefaultHttpClient();
                HttpGet request = new HttpGet("http://demo.tugain.com/tapme/RetriveMap.php?q=cat");
                HttpResponse response = client.execute(request);
                HttpEntity entity=response.getEntity();
                data=EntityUtils.toString(entity);
                Log.e("STRING", data);
                try 
                {
                   JSONArray json=new JSONArray(data);
                   for(int i=0;i<json.length(); i++)
                   {
                        JSONObject obj=json.getJSONObject(i);

                        Location=obj.getString("Location");
                        Latitude=obj.getString("Latitude");
                        Longitude=obj.getString("Longitude");

                        Log.e("STRING", Location);
                        Log.e("STRING",Latitude);
                        Log.e("STRING",Longitude);

                        r.add(Location);
                        r1.add(Latitude);
                        r2.add(Longitude);
                        Map<String, String> datum = new HashMap<String, String>();
                        datum.put("Loc",Location);
                        datum.put("Lat", Latitude);
                        datum.put("Long", Longitude);
                        data1.add(datum);
                   }
                } 
                catch (JSONException e) 
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            } catch (ClientProtocolException e) {
                Log.d("HTTPCLIENT", e.getLocalizedMessage());
            } catch (IOException e) {
                Log.d("HTTPCLIENT", e.getLocalizedMessage());
            }
    }
}

But I am not getting even map. The app stopped with "Unfortunately Stopped".In Logcat, it displays error at googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); What is wrong with my code..?? And is this code will display all locations that will retrieved from mysql database..?? Please help me..!!!