在运行Google Map v2时不断更新标记

Question

我正在创建一个跟踪应用，通过短信从用户接收数据（经度和纬度）并在googlemapv2上显示。我希望我的应用程序能够连续工作，并在收到新消息时在新位置更新标记。但是标记不会移动到新位置。 我已经制作了2个java文件。一个是接收新短信的“IncomingSms”，另一个是显示谷歌地图和显示标记的“MainActivity”。它在默认位置显示标记，但不在新坐标上更新。 请帮帮我......这是我的代码..

package com.example.chck;




public class MainActivity extends Activity {

public static LatLng point;
GoogleMap gMap;

@Override
public void onNewIntent(Intent intent) {
super.onNewIntent(intent);
setIntent(intent);
Log.d("Activity","Got new Data again");
Toast.makeText(getApplicationContext(),"In NEW-INTENT", Toast.LENGTH_SHORT).show();
initializeMap();
drawMarker();

} 



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    gMap =   ((MapFragment)getFragmentManager().findFragmentById(R.id.MyMap)).getMap();
    initializeMap();
    Toast.makeText(getApplicationContext(),"In CREATE", Toast.LENGTH_SHORT).show();

                    // Enabling MyLocation Layer of Google Map
                    gMap.setMyLocationEnabled(true);


    }


private void drawMarker(){
    // Clears all the existing coordinates

    String LON="72.99056966";
    String LAT="33.64272895";
    gMap.clear();


    if(IncomingSms.chk==1){
        Intent i1 = getIntent();
        LAT = i1.getExtras().getString("NewLat");
        LON = i1.getExtras().getString("NewLon");
    }


    Toast.makeText(getBaseContext(),LAT + LON , Toast.LENGTH_SHORT).show();
    point = new LatLng(Double.parseDouble(LAT), Double.parseDouble(LON));


    // Creating an instance of MarkerOptions
    MarkerOptions markerOptions = new MarkerOptions();

    // Setting latitude and longitude for the marker
    gMap.clear();
    markerOptions.position(point);

    // Setting title for the InfoWindow
    markerOptions.title("Position");

    // Setting InfoWindow contents
    markerOptions.snippet("Latitude:"+point.latitude+",Longitude"+point.longitude);

    // Adding marker on the Google Map
    gMap.addMarker(markerOptions);

    // Moving CameraPosition to the user input coordinates
    gMap.moveCamera(CameraUpdateFactory.newLatLng(point));

}

private void initializeMap() {

    if (gMap == null) {
    gMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.MyMap)).getMap();

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


@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;
}

}

========================

IncomingSms.java

package com.example.chck;



public class IncomingSms extends BroadcastReceiver {

public static double latitude;
public static double longitude;
public static int chk =0;
public static String la;
public static String lo;
// Get the object of SmsManager
final SmsManager sms = SmsManager.getDefault();

public void onReceive(Context context, Intent intent) {

    // Retrieves a map of extended data from the intent.
    final Bundle bundle = intent.getExtras();

    try {

        if (bundle != null) {

            final Object[] pdusObj = (Object[]) bundle.get("pdus");

            for (int i = 0; i < pdusObj.length; i++) {

                SmsMessage currentMessage = SmsMessage
                        .createFromPdu((byte[]) pdusObj[i]);
                String phoneNumber = currentMessage
                        .getDisplayOriginatingAddress();

                String senderNum = phoneNumber;
                String message = currentMessage.getDisplayMessageBody();

                String[] columns = message.split(",");
                assert columns.length == 2;
             longitude = Double.parseDouble(columns[0]);
             latitude = Double.parseDouble(columns[1]);
             la= columns[1];
             lo= columns[0];

                Log.i("SmsReceiver", "senderNum: " + senderNum
                        + "; message: " + message);

                int duration = Toast.LENGTH_LONG;
                 //Toast toast = Toast.makeText(context, "Latitude: "+
                 //longitude + ", Longitude: " + latitude, duration);
                 //toast.show();

            } // end for loop


             chk=1;
                //New Location fetched

                Toast.makeText(context,la + lo , Toast.LENGTH_SHORT).show();

                final Intent i1 = new Intent(context, MainActivity.class);
                i1.putExtra("NewLat", la);
                i1.putExtra("NewLon", lo);
                int duration1 = Toast.LENGTH_LONG;
                //Toast toast1 = Toast.makeText(context, "Check Latitude: "+
                    //   lo + ", Longitude: " + la, duration1);
                 //toast1.show();

        } // bundle is null

    } catch (Exception e) {
        Log.e("SmsReceiver", "Exception smsReceiver" + e);

    }
}

}