public void checkFields (LYNXsys system) { // check textfields before adding student to system
		boolean existingStudentFlag = false; // temp var to flag if student info is valid
		if (!(getFirstName().getTextField().getText().equals("")) && // check that ALL FIELDS are filled (4)
					!(getLastName().getTextField().getText().equals("")) &&
					!(getID().getTextField().getText().equals("")) && 
					!(getPassword().getTextField().getText().equals(""))) { // end check
			for (int i = 0; i < system.getUsers().size(); i ++) { // loop through all users
				if (getID().getTextField().getText().equalsIgnoreCase(system.getUsers().get(i).getID())){ // check if user is already in system or not
					existingStudentFlag = true; // if so, set true ... addStudent method will not be called
				}
			}
		}
		if (!existingStudentFlag) { // if flag is never flipped true, this code will run
			system.addStudent(new User (getFirstName().getTextField().getText(), getLastName().getTextField().getText(), getID().getTextField().getText(),getPassword().getTextField().getText()));
		}
	}