@Override
    public void updateCoordinates(@Nullable final Geopoint gp) {
        //this method is supposed to update the "base" / "preprojected" coordinate
        if (!Objects.equals(preprojectedCoords, gp)) {
            preprojectedCoords = gp;
            recalculateProjectionView();
        }
        ((MaterialButton) binding.buttonLatLongitude).setIconResource(CalculatedCoordinate.isValidConfig(calcStateString) ? R.drawable.ic_menu_variable : 0);
    }
this method assumes a correctly filled "preprojectedCoord"-var.
It recalculates the "currentCoord" value and updates view according to projection settings
main/src/main/java/cgeo/geocaching/EditWaypointActivity.java