Here are some points:
My code snippet
private boolean isAnyMarkerVisible(LatLng ll) {
if(gMap != null && markersData != null) {
final LatLngBounds latLongBounds = LatLngBounds.builder().include(ll).build();
for (Store store : markersData) {
if (latLongBounds.contains(store.getLatLng())) {
return true;
}
}
}
return false;
}