you can use this function. I have used it in my project.
public String getDistance(LatLng my_latlong, LatLng frnd_latlong) {
Location l1 = new Location("One");
l1.setLatitude(my_latlong.latitude);
l1.setLongitude(my_latlong.longitude);
Location l2 = new Location("Two");
l2.setLatitude(frnd_latlong.latitude);
l2.setLongitude(frnd_latlong.longitude);
float distance = l1.distanceTo(l2);
String dist = distance + " M";
if (distance > 1000.0f) {
distance = distance / 1000.0f;
dist = distance + " KM";
}
return dist;
}