This is the best way to detect Bearing from Location Object on Google Map:->
float targetBearing=90;
Location endingLocation=new Location("ending point");
Location
startingLocation=new Location("starting point");
startingLocation.setLatitude(mGoogleMap.getCameraPosition().target.latitude);
startingLocation.setLongitude(mGoogleMap.getCameraPosition().target.longitude);
endingLocation.setLatitude(mLatLng.latitude);
endingLocation.setLongitude(mLatLng.longitude);
targetBearing =
startingLocation.bearingTo(endingLocation);