Custom Exceptions Class Naming in Java

Question

I am trying to create a custom exception class but having trouble naming. Here's what I have so far:

public class MyException extends Exception {
     public MyException() {
     }
}

Now, I want an exception that is not called MyException. Can I use:

public void EmptyException() {
}

Thank you for your help.

Answer 1

yes ofcourse, just do the same thing again :) create a new class called EmptyException

in same class:

    public class EmptyException extends Exception {
         public EmptyException() {
         }
        public class InnerException extends Exception { //Inner class
           public InnerException() {
               }

          }
    }

Answer 2

Prefer creating one exception per file:

Within MyException.java:

public class MyException extends Exception {
    //useless to define here the default constructor
}

Within EmptyException.java

public class EmptyException extends Exception {
    //useless to define here the default constructor
}

In this case, using inner-classes = code smell.

If both exceptions are really linked together, prefer inheritance over inner-classing:

public class EmptyException extends MyException {
  //useless to define here the default constructor since parent's constructor is zero-arg one.
}