Unreported Exception error message

Question

( Error message:
AddStudentException must be caught or declared to be thrown)
Can anyone explain the error message above from this code?
public class Course
public void addStudent(Student s) throws AddStudentException
public static void main(String[] stringArray)
Course c1 = new Course("CS110",3);
Student s1 = new Student("Dave");
CourseAlreadyPassedException message =
new CourseAlreadyPassedException
("This course has already been taken. ");
c1.addStudent(s5);
public abstract class AddStudentException extends Exception {
// Constructors
public AddStudentException() { }
public AddStudentException(String message)
super (message);
public class CourseAlreadyPassedException extends AddStudentException {
// Constructors
public CourseAlreadyPassedException() { }
public CourseAlreadyPassedException(String message)
super (message);

Answer 1

You've declared that a call to addStudent may throw an AddStudentException. So the caller (the main() method in this case) must either:
A) handle the exception via try/catch blocks
try {
... call the method here ...
catch (AddStudentException e) {
... do something about the exception here
or
B) declare that it also throws the exception
public static void main(...) throws AddStudentException