StudentUtilsTester

public class StudentTester {

    public static void main(String[] args) {

        Student s1 = new Student("ABC", "XYZ", "California", "1234");
        System.out.println(StudentUtils.checkInformation(s1)); // print toString()

        System.out.println();

        Student s2 = new Student("FIRST","LAST", "SWEDEN", "abc123ewf8f98f89");
        System.out.println(StudentUtils.checkInformation(s2)); // print null
    }
}