How to clear the Overlay using GWT - gwt

Question

I have a class which I used to overlay rectangles on maps. But I am not able to figure out how to remove the previous overlay's to draw new rectangles if a new set of results are provided to my displayOnMap method.
To provide more insight on the draw method. It takes in PlotSetOutput as an argument which contains centers and each center contains a set of lat/long co-ordinates. Hence the logic for looping over it and creating lat/long bounds and assigning it to rectangle objects.
public class displayOnMap extends Composite {
private final VerticalPanel pWidget;
private MapWidget mapWidget;
private static Rectangle rectangle;
private RectangleOptions rectOpts;
private static final LatLng USCENTER = LatLng.newInstance(33.68,-116.17);
public displayOnMap(PlotSetOutput result) {
pWidget = new VerticalPanel();
initWidget(pWidget);
draw(result);
}
private void draw(PlotSetOutput result) {
MapOptions mapOpts = MapOptions.newInstance();
mapOpts.setZoom(4);
mapOpts.setCenter(USCENTER);
mapOpts.setMapTypeId(MapTypeId.TERRAIN);
mapWidget = new MapWidget(mapOpts);
pWidget.add(mapWidget);
mapWidget.setSize("800px", "800px");
ArrayList<Centers> listOfCenters = new ArrayList<Centers>();
List<ResultClusterPlots> finalCluster = result.getFinalcluster();
int totalNumberOfClusters = result.getTotalNumberOfClusters();
for (int i = 0; i < totalNumberOfClusters; i++) {
listOfCenters.add(i, new Centers());
}
for (int j = 0; j < finalCluster.size(); j++) {
Centers p = listOfCenters.get(finalCluster.get(j).getClusterID()-1);
LatLng ne = LatLng.newInstance(finalCluster.get(j).getLatitude()
.get(0), finalCluster.get(j).getLongitude().get(0));
LatLng sw = LatLng.newInstance(finalCluster.get(j).getLatitude()
.get(1), finalCluster.get(j).getLongitude().get(1));
p.setLatLongArr(LatLngBounds.newInstance(ne,sw));
}
for (int k = 0; k < listOfCenters.size(); k++) {
ArrayList<LatLngBounds> ltlgBound = listOfCenters.get(k).getLatLongArr();
String color = getRandomColor();
for (int l = 0; l < ltlgBound.size(); l++) {
rectOpts = RectangleOptions.newInstance();
rectOpts.setStrokeColor("#FF0000");
rectOpts.setStrokeOpacity(0.3);
rectOpts.setStrokeWeight(2);
rectOpts.setFillColor(color);
rectOpts.setFillOpacity(0.35);
rectOpts.setMap(mapWidget);
rectOpts.setBounds(ltlgBound.get(l));
rectangle = Rectangle.newInstance(rectOpts);
rectangle.setMap(mapWidget);
}
}
}
}
Output when the method (displayOnMap) is invoked for the first time. Everything works fine.
Output when the displayOnMap method is called with a second query.
I tried to do rectangle.setMap(null); pWidget.removeFromParent(); but I kept getting the same result.

Answer 1

I have had the same problem, the only way I could hide / delete / show the overlays was through the OverlayCompleteMapEvent.
As I understand it isn't possible to get a hook to an overlay before it is completed, once it is completed the only way to get a hook on it is handling "OverlayCompleteMapEvent" event. I used a list to store the Overlays and then I could hide/show/delete them.