double longitude = minLon + (double)(Math.random() * ((maxLon - minLon) + 1));
GLatLng glatlng = new GLatLng(latitude, longitude);
markersToShow.add(glatlng);
map.addOverlay(new GMarker("marker"+i, new GMarkerOptions(map, glatlng)));
mapDefault.addOverlay(new GMarker("marker"+i, new GMarkerOptions(mapDefault, glatlng)));
}
// set some options
GMarkerClusterOptions options = new GMarkerClusterOptions();
options.setMinimumClusterSize(3);