You cant do UI operations from background thread.
Try this:
GraphHopper tmpHopp = new GraphHopper().forAndroid();
tmpHopp.contractionHierarchies(true);
tmpHopp.load(mapsFolder + currentArea);
runOnUiThread(new Runnable() {
public void run() {
logUser("found graph with " + tmpHopp.getGraph().nodes() + " nodes");
}
});
hopper = tmpHopp;
return null;