What is Java Custom Exception?

Java Custom Exception

Custom exceptions are exceptions that we can create on our own by inheriting Exception class. This how we can use all the functionalities of the exception class. Java custom exceptions are used to customize the exception according to user need. Here is an example-

1. package com.Akshay.exceptions;
2. /**@author Akshay Ingole**/
3. public class InvalidUserNameException extends Exception {
4. private static final long serialVersionUID = 1L;
5. InvalidUserNameException(String s) {
6. super(s);
7. }
8. }

Now your test program is

package com.Akshay.exceptions;
/** @author Akshay Ingole**/
public class TestException {
 public static void validateName(String name) throws InvalidUserNameException {
  if (" ".equalsIgnoreCase(name) || null == name)
   throw new InvalidUserNameException("Name is not valid");
  else
   System.out.println("Hello " + name);
 }
 public static void main(String args[]) {
 try {
   validateName("Akshay");
   validateName(" ");
  } catch (Exception e) {
   System.out.println("Exception occured: " + e);
  }
 }
}


Output
Hello Akshay
Exception occured: com.Akshay.exceptions.InvalidUserNameException: Name is not valid

Hope this will helps you.