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Question

I'm developing an android application and I have a google map on one of the activities. The map contains a marker and the coordinates of the marker will be updated every 10 seconds. The coordinates will be obtained from a server. Question: How do I update the marker's position on the map?

Here is what my mapsActivity.java looks like:

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

private GoogleMap mMap;

private String lat = "-25.4316562";
private String lon = "50.6602371";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

}

public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    LatLng sydney = new LatLng(-100, 35);
    mMap.addMarker(new MarkerOptions().position(sydney).title("Marker on the drone"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
    CameraUpdate zoom=CameraUpdateFactory.zoomTo(17);
    mMap.animateCamera(zoom);
}

I have 2 functions that will update the global variables lat and lon by sending SSH commands to the server:

new getXCoordinates().execute();
new getYCoordinates().execute();

I tried calling a function to update the coordinates and marker in the OnCreate function, but that's not working. I cant find out how to call a function repeatedly after 10 seconds to update the marker.

Answer 1

You can use something like this:

Handler h = new Handler();
int delay = 10 * 1000;

h.postDelayed(new Runnable(){
    public void run(){

        // This portion of code runs each 10s.

        h.postDelayed(this, delay);
    }
}, delay);

to add a marker you should use

yourMarker = googleMap.addMarker(new MarkerOptions().position(latlng))

and to update use

yourMarker.setPosition(latlng);

The key here is to retain an instance of the created marker so you can change its position at will.