Set - 9

Question 56 :

How to create custom exceptions?

Answer :

Your class should extend class Exception, or some more specific type thereof.


Question 57 :

If I want an object of my class to be thrown as an exception object, what should I do?

Answer :

The class should extend from Exception class. Or you can extend your class from some more precise exception type also.


Question 58 :

If my class already extends from some other class what should I do if I want an instance of my class to be thrown as an exception object?

Answer :

One can not do anything in this scenario. Because Java does not allow multiple inheritance and does not provide any exception interface as well.


Question 59 :

How does an exception permeate through the code?

Answer :

An unhandled exception moves up the method stack in search of a matching When an exception is thrown from a code which is wrapped in a try block followed by one or more catch blocks, a search is made for matching catch block. If a matching type is found then that block will be invoked. If a matching type is not found then the exception moves up the method stack and reaches the caller method. Same procedure is repeated if the caller method is included in a try catch block. This process continues until a catch block handling the appropriate type of exception is found. If it does not find such a block then finally the program terminates.


Question 60 :

What are the different ways to handle exceptions?

Answer :

There are two ways to handle exceptions,
1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and
2. List the desired exceptions in the throws clause of the method and let the caller of the method handle those exceptions.