public Student search(int id) throws UnknownStudent {
		Student s = null;
		boolean found = false;
		int i = 0;

		while (i < list.size() && !found) {
			s = list.get(i);
			if (s.getId() == id)
				found = true;
			i++;
		}

		if (!found) {
			throw new UnknownStudent("No student with an id " + id
					+ " in the Promotion " + name + " !");
		} else {
			return s;
		}
	}