Why should we write custom exception classes in Java

Question

What is the purpose of writing custom exception classes when mostly what it does is same. For eg, NullPointerException:

class NullPointerException extends Ru         


        

Answer 1

I can think of several reasons:

• Having multiple exception classes allows the programmer to be specific in their catch clauses, and only catch the exceptions they care about and know what to do with.
• An exception class can carry information about the error that's caused the exception. For example, ArrayIndexOutOfBoundsException carries the offending array index, and SQL exceptions tends to carry database-specific error codes and messages.
• Exception specifications -- that list exception classes -- can be used to check correctness at compile time.