// I want to try making my OWN exception, to handle a
// numeric grade NOT in a "legal" range;

public class BadGradeException extends Exception
{
    public BadGradeException(Number badGrade)
    {
        // acc to "Java Precisely", p. 55: "Passing a string to the
        // constructor of the superclass (that is, class Exception)
        // causes method toString to append that string to the
        // name of the exception."
        super("Bad grade value:" + badGrade);
    }
}