How to remove Marker and redraw it again when chan

问题:

////Before editing

I am using the below code to redraw a Marker on android map, actually it redraw a marker but it doesn't remove the old one, I tried

mapView.invlaidate

but it didn't remove the old one.

Here is the onLocationChanged function:

   @Override
 public void onLocationChanged(Location location) {
    // mapView.invalidate();

        //getCurrantPoint();
         OverlayItem currentOverlay = new OverlayItem(getCurrantPoint(),"Current Location","Here is my current location!!!");

            itemizedoverlay2.addOverlay(currentOverlay);
            mapOverlays.add(itemizedoverlay2);
            mapOverlays.remove(currentOverlay);
            Log.v("TAG", "Removeeeeeeeeeeeeeeeed");

         ///
         //mapOverlays.add(itemizedoverlay);
 }

Thanks in Advance.

/////After editing

 if(itemizedoverlay2!=null)
     {
         mapOverlays.remove(itemizedoverlay2);

         itemizedoverlay2 = new HelloItemizedOverlay(drawable2, cntxt);
         OverlayItem currentOverlay = new OverlayItem(getCurrantPoint(),"Current Location","Here is my current location!!!");
         itemizedoverlay2.addOverlay(currentOverlay);

         mapOverlays.add(itemizedoverlay2);
     }
     else
     {
            itemizedoverlay2 = new HelloItemizedOverlay(drawable2, cntxt);

            OverlayItem currentOverlay = new OverlayItem(getCurrantPoint(),"Current Location","Here is my current location!!!");
            itemizedoverlay2.addOverlay(currentOverlay);
            mapOverlays.add(itemizedoverlay2);

     }

Big thanks to imran khan and agarwal; I used your answers to debug the problem.

回答1:

try this:

OverlayItem currentOverlay = new OverlayItem(getCurrantPoint(),"Current Location","Here is my current location!!!");
itemizedoverlay2.addOverlayItem(currentOverlay);
mapOverlays.getOverlays().add(itemizedoverlay2);
mapOverlays.getOverlays().remove(itemizedoverlay2);
mapOverlays.invalidate();
Log.v("TAG", "Removeeeeeeeeeeeeeeeed");

//mapOverlays is your mapView obejct and itemizedoverlay2 is your LocationOverlay

remove LocationOverlay i.e itemizedoverlay2 instead of OverlayItem

回答2:

try this:::

@Override public void onLocationChanged(Location location) { // mapView.invalidate();

    //getCurrantPoint();
     OverlayItem currentOverlay = new OverlayItem(getCurrantPoint(),"Current Location","Here is my current location!!!");
        itemizedoverlay2.clear();
        itemizedoverlay2.addOverlay(currentOverlay);
       //in above line create new itemizedoverlay2 every time.
        mapOverlays.clear();
        mapOverlays.add(itemizedoverlay2);            

     ///
     //mapOverlays.add(itemizedoverlay);

}

Updated have a look:::

A typical custom overlay looks like this. it encapsulates the various OverlayItems displayed on the map in a list.

public class MyItemizedOverlay extends ItemizedOverlay<OverlayItem>{

    private List<OverlayItem> mOverlays = new ArrayList<OverlayItem>();

    public MyItemizedOverlay(Drawable defaultMarker) {
        super(boundCenterBottom(defaultMarker));        
    }

    @Override
    protected OverlayItem createItem(int i) {
        return mOverlays.get(i);
    }

    public void addOverlay(OverlayItem overlay) {
        mOverlays.add(overlay);
        populate();
    }

    public void removeOverlay(OverlayItem overlay) {
        mOverlays.remove(overlay);
        populate();
    }


    public void clear() {
        mOverlays.clear();
        populate();
    }

    @Override
    public int size() {
        return mOverlays.size();
    }
}

Methods can be exposed to add / remove individual overlayitems, but also the remove all overlayitems (clear method).

Remove a single overlayitem

MyItemizedOverlay sitesOverlay =  (MyItemizedOverlay ) map.getOverlays().get(0);
sitesOverlay.removeOverlay(overlay);

Add a single overlayItem

MyItemizedOverlay sitesOverlay =  (MyItemizedOverlay ) map.getOverlays().get(0);
sitesOverlay.addOverlay(new OverlayItem(p, "title", "snippet"));

Remove all overlayItems

MyItemizedOverlay sitesOverlay =  (MyItemizedOverlay ) map.getOverlays().get(0);
sitesOverlay.clear();

回答3:

Why to reinvent your own distance calculator, there is one built into the Location class.

Check out

distanceBetween(double startLatitude, double startLongitude, double endLatitude, double endLongitude, float[] results) 

Computes the approximate distance in meters between two locations, and optionally the initial and final bearings of the shortest path between them.