public static ArrayList<Long> loadIsbns(String filename) {
		ArrayList<Long> toBeAdded = new ArrayList<Long>();

		try {
			Scanner fileIn = new Scanner(new File(filename));
			int lineNum = 1;

			while (fileIn.hasNextLine()) {
				String line = fileIn.nextLine();

				Scanner lineIn = new Scanner(line);
				lineIn.useDelimiter("\\t");

				if (!lineIn.hasNextLong())
					throw new ParseException("ISBN", lineNum);
				long isbn = lineIn.nextLong();

				toBeAdded.add(isbn);
				lineNum++;
			}
		} catch (FileNotFoundException e) {
			System.err.println(e.getMessage() + " Nothing added to the library.");
			return null;
		} catch (ParseException e) {
			System.err.println(e.getLocalizedMessage()
					+ " formatted incorrectly at line " + e.getErrorOffset()
					+ ". Nothing added to the library.");
			return null;
		}
		return toBeAdded;
	}