In the class graderoll, a nine-digit student identification number is reported with a code consisting five leading Xs and the last four digits. For instance the code for Student ID XXXXXXXXXXis...

In the class graderoll, a nine-digit student identification number is reported with a code consisting five leading Xs and the last four digits. For instance the code for Student ID 999-44-8901 is XXX-XX-8901. Write a method that takes as input an array consisting of student identification numbers and returns a List containing all codes that correspond to two or more students.