move marker on google maps api 2

Question

How do I move marker on Google maps api V2 ? I am using below code but it does not move marker on the map. What am I doing wrong here ? This should work when location changes, so I have added onLocationChanged method and in that, am getting location details and trying to move marker on new details, but this doesn't work.

Here is my code:

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;

import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.gson.Gson;

public class MapViewActivity extends Activity implements LocationListener,
        SensorEventListener, OnClickListener {

    GoogleMap googleMap;

    private boolean started = false;
    private ArrayList<AccelLocData> sensorData;
    private SensorManager sensorManager;
    private Button btnStart, btnStop;
    private String provider;

    // File root, dir, sensorFile;
    FileOutputStream fOut;
    private Sensor mAccelerometer;
    private FileWriter writer;
    private DatabaseHelper databaseHelper;
    private BroadcastReceiver alarmReceiver;
    private PendingIntent pendingIntentSender, pendingIntentReceiver;

    private AlarmManager alarmManager;
    private Intent alarmIntent,alarmIntent2;

    // private Button btnUpload;

    @SuppressLint("NewApi")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        try {

            databaseHelper = new DatabaseHelper(this);
            databaseHelper.removeAll();


            Log.v("datacount",
                    Integer.toString(databaseHelper.getLocDataCount()));

            sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
            mAccelerometer = sensorManager
                    .getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

            btnStart = (Button) findViewById(R.id.btnStart);
            btnStop = (Button) findViewById(R.id.btnStop);
            btnStart.setOnClickListener(this);
            btnStop.setOnClickListener(this);
            btnStart.setEnabled(true);
            btnStop.setEnabled(false);

            alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);

            int status = GooglePlayServicesUtil
                    .isGooglePlayServicesAvailable(getBaseContext());
            if (status != ConnectionResult.SUCCESS) { // Google Play Services
                                                        // are
                                                        // not available

                int requestCode = 10;
                Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status,
                        this, requestCode);
                dialog.show();

            } else { // Google Play Services are available

                // Getting reference to the SupportMapFragment of
                // activity_main.xml
                // SupportMapFragment supportMapFragment = (MapFragment)
                // getFragmentManager().findFragmentById(R.id.map);

                // Getting GoogleMap object from the fragment
                googleMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();


                // can use for overlay on the map
                List<Double> latList = new ArrayList<Double>();
                latList.add(145.7309593);
                latList.add(146.34);
                latList.add(147.34);

                List<Double> lonList = new ArrayList<Double>();
                lonList.add(-122.6365384);
                lonList.add(-123.6365384);
                lonList.add(-124.6365384);

                for (int i = 0; i < 3; i++) {
                    // LatLng latLng = new LatLng(45.7309593, -122.6365384);
                    LatLng latLng = new LatLng(latList.get(i).doubleValue(),
                            lonList.get(i).doubleValue());
                    googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
                    googleMap
                            .addMarker(new MarkerOptions()
                                    .position(latLng)
                                    .title("My Spot")
                                    .snippet("This is my spot!")
                                    .icon(BitmapDescriptorFactory
                                            .defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
                }

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

                LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

                Criteria criteria = new Criteria();
                provider = locationManager.getBestProvider(criteria, true);
                Location location = locationManager
                        .getLastKnownLocation(provider);

                if (location != null) {
                    onLocationChanged(location);
                }

                locationManager
                        .requestLocationUpdates(provider, 20000, 0, this);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public void onSensorChanged(SensorEvent event) {

        if (started) {

            double x = event.values[0];
            double y = event.values[1];
            double z = event.values[2];

            long timestamp = System.currentTimeMillis();

            LocationManager locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            criteria.setPowerRequirement(Criteria.POWER_MEDIUM);
            criteria.setAccuracy(Criteria.ACCURACY_FINE);

            provider = locManager.getBestProvider(criteria, true);
            Location location = locManager.getLastKnownLocation(provider);

            double latitude = 0;
            double longitude = 0;
            if (location != null) {
                latitude = location.getLatitude();
                longitude = location.getLongitude();
            }
            AccelLocData accelLocData = new AccelLocData(timestamp, x, y, z,
                    latitude, longitude);

            // Log.d("X data","data x:" + data.getX());

            try {
                // writer.write(data.toString());
                 if (databaseHelper != null)
                 databaseHelper.insertLocData(accelLocData);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }

    @Override
    public void onLocationChanged(Location location) {

        TextView tvLocation = (TextView) findViewById(R.id.tv_location);

        // Getting latitude of the current location
        double latitude = location.getLatitude();

        // Getting longitude of the current location
        double longitude = location.getLongitude();

        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);

        // Showing the current location in Google Map
        googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));






    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.btnStart:

            Context context = getApplicationContext();
            alarmIntent = new Intent(context, AccelLocSender.class);

            AlarmManager alarmManager = (AlarmManager) context
                    .getSystemService(Context.ALARM_SERVICE);
            pendingIntentSender = PendingIntent.getBroadcast(context, 0,
                    alarmIntent, 0);

            alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
                    System.currentTimeMillis(), 60000, pendingIntentSender);

            alarmIntent2 = new Intent(context, AccelLocReceiver.class);
            pendingIntentReceiver = PendingIntent.getBroadcast(context, 0,
                    alarmIntent2, 0);
            alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
                    System.currentTimeMillis(), 30000, pendingIntentReceiver);

            btnStart.setEnabled(false);
            btnStop.setEnabled(true);
            Log.d("startbutton", "cam on click of start");
            started = true;

            // delete all files..
            // start thread to send data

            sensorManager.registerListener(this, mAccelerometer,
                    SensorManager.SENSOR_DELAY_FASTEST);
            break;
        case R.id.btnStop:
            try {
                btnStart.setEnabled(true);
                btnStop.setEnabled(false);
                // btnUpload.setEnabled(true);
                started = false;

                sensorManager.unregisterListener(this);

                Context context1 = getApplicationContext();
                AlarmManager alarmManager1 = (AlarmManager) context1
                        .getSystemService(Context.ALARM_SERVICE);
                alarmManager1.cancel(pendingIntentSender);
                alarmManager1.cancel(pendingIntentReceiver);

            //  System.exit(0);

                } catch (Exception e) {
                e.printStackTrace();
            }
            break;
        default:
            break;
        }

    }

    protected void onPause() {
        super.onPause();

        /*
         * if (writer != null) { try { writer.close(); } catch (IOException e) {
         * // TODO Auto-generated catch block e.printStackTrace(); } }
         */
    }

    protected void onResume() {
        super.onResume();
        /*
         * try { Log.d("onresume","called onresume"); writer = new
         * FileWriter(sensorFile, true); } catch (IOException e) { // TODO
         * Auto-generated catch block e.printStackTrace(); }
         */
    }

    @Override
    public void onProviderDisabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onAccuracyChanged(Sensor arg0, int arg1) {
        // TODO Auto-generated method stub

    }

}

Answer 1

Make variable

 Marker now;

in this part add Marker and remove marker, of course put in the rest of your marker attributes:

 @Override
public void onLocationChanged(Location location) {

    if(now != null){
                now.remove();

            }

    TextView tvLocation = (TextView) findViewById(R.id.tv_location);

    // Getting latitude of the current location
    double latitude = location.getLatitude();

    // Getting longitude of the current location
    double longitude = location.getLongitude();

    // Creating a LatLng object for the current location
    LatLng latLng = new LatLng(latitude, longitude);
    now = googleMap.addMarker(new MarkerOptions().position(latLng)));
    // Showing the current location in Google Map
    googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

    // Zoom in the Google Map
    googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));

}