StudentUtils

public class StudentUtils {

    public static String checkInformation(Student student) {
        String studentFirst = student.getFirstName();
        String studentLast = student.getLastName();
        String address = student.getAddress();
        String idNumber = student.getStudentNumber();

        if (student == null) {
            return null;
        } else if (studentFirst.isEmpty() || studentFirst == null
                && studentLast.isEmpty() || studentLast == null
                && address.isEmpty() || address == null
                && idNumber.isEmpty() || idNumber == null) {
            return null;
        } else {
            for (char c : idNumber.toCharArray()) {
                if (!Character.isDigit(c)) {
                    return null;
                } // end if
            } // end for
            return student.toString();
        }
    }
}