In Java, the report.txt must list the students sorted by either the gpa or number of credit hours. Use the Java Comparator interface to sort the students. For that, copy the Student objects into an ArrayList that you sort by gpa or by credit hours - use the code provided:

 

for (int i = 0; i < count; i++){

if (persons[i] instanceof Student)

persons[i].report(myWriter);

}
myWriter.close();