class References {
	public static void main(String[] args) {
		Student s1 = new Student(300012345, "userid");
		s1.setFirstName("Rudiger");
		Student s2 = s1;
		s2.setFirstName("Bart");
		
		System.out.println( s1.getFirstName() );
		System.out.println( s2.getFirstName() );
	}
}