Step to reproduce:
1. To set up, run
 	network = Network.getInstance();
	network.initializationStations();
	network.initializationLines();
2. To get the Tuen Mun station, run:
        Station tuenmun = network.searchStationByName("Tuen Mun");
3. To get the name of the searched station, run:
        String result = tuenmun.getName();

Expected result: Tuen Mun
Actual result: NullPointerException

From the NullPointerException, I made a safe assumption that the search returned null. I have made some experiments to search other station names and yet none of them seemed to have this problem.

Please check what is causing this problem.