READING
CHAPTER 8
SECTION 5
"Programmer-Defined Exceptions"

- define our own exception classes
  - instead of using generic exception classes
  - lets us write methods to provide more useful information
  - make the new exception class a subclass of Exception
    - because want programmers to have to catch the exception: use a checked exception
    - syntax
      
      <visibility modifier> class <class name> extends Exception {}

Quick Check:
1. We want to define a customized exception class when the existing classes don't allow us to access enough information about the exception.
2. A customized exception class should be a checked exception.