如何在触摸时删除项目叠加并在触摸时添加另一个项目叠加层

Question

这是MapOverlay：

class MapOverlay extends com.google.android.maps.Overlay
{
    @Override
    public boolean draw(Canvas canvas, MapView mapView, 
    boolean shadow, long when) 
    {
            return true;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event, MapView mapView) 
    {   
        //---when user lifts his finger---
        if (event.getAction() == 1) {                
            GeoPoint p = mapView.getProjection().fromPixels(
                (int) event.getX(),
                (int) event.getY());

            List<Overlay> mapOverlays = mapView.getOverlays();
            Drawable drawable = getResources().getDrawable(R.drawable.splash_logo);
            ItemizedOverlay itemizedoverlay = new ItemizedOverlay(drawable, getApplicationContext());
            OverlayItem overlayitem = new OverlayItem(p, "I'm in LA!");
            itemizedoverlay.addOverlay(overlayitem);
            mapOverlays.add(itemizedoverlay);
            mapView.invalidate();
            Geocoder geoCoder = new Geocoder(
                getBaseContext(), Locale.getDefault());
            try {
                List<Address> addresses = geoCoder.getFromLocation(
                    p.getLatitudeE6()  / 1E6, 
                    p.getLongitudeE6() / 1E6, 1);
                 String add = "";
                if (addresses.size() > 0) 
                {
                    for (int i=0; i<addresses.get(0).getMaxAddressLineIndex(); 
                         i++)
                       add += addresses.get(0).getAddressLine(i) + "n";
                }
                //Toast.makeText(getBaseContext(), add, Toast.LENGTH_SHORT).show();
                addr = add;
            }
            catch (IOException e) {                
                e.printStackTrace();
            }   
            return true;
        }
        else                
            return false;
    }        
}

这是逐项叠加：

class ItemizedOverlay extends com.google.android.maps.ItemizedOverlay<OverlayItem>{

    private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();
    private Context mContext;
    public ItemizedOverlay(Drawable defaultMarker) {
     super(boundCenterBottom(defaultMarker));
    // TODO Auto-generated constructor stub
    }
    public ItemizedOverlay(Drawable defaultMarker, Context context) {
      super(boundCenterBottom(defaultMarker));
      mContext = context;
    }
    @Override
    protected OverlayItem createItem(int i) {
      return mOverlays.get(i);
    }
    @Override
    public int size() {
      return mOverlays.size();
    }
    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
    protected boolean onTap(int index) {
      OverlayItem item = mOverlays.get(index);
      AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
      dialog.setTitle(item.getTitle());
      dialog.setMessage(item.getSnippet());
      dialog.show();
      return true;
    }
}

我能够添加多个项目覆盖，但无法调用 clear，以便删除项目ziedoverylay项目。

我想做的是：当我触摸地图的特定点时，应该删除以前的逐项叠加，并在该点创建一个新的叠加层。我知道我必须调用 clear（），但无法弄清楚我应该在哪里做。

Answer 1

嗨，

你必须在你的映射覆盖类中编写这段代码

if (itemizedoverlay != null) { itemizedoverlay.overlayClear(); }