Custom Exception
How to create a custom exception ?
Write code to create a Custom Exception
All these are questions usually asked in a Java interview .So my today's post on how to create a custom exception in java .
As we know There are two types of Exception :
1. Checked Exception
2. Unchecked Exception
Both these exceptions have a common parent class Exception .So ,in same order if we have to create a custom exception ,we need to extend Exception class.
Ok , let me explain the process step by step .
1. Any custom exception should extend Exception Class .
2. There should be a proper name given to the Exception ,For example if there is an exception related to Invalid age name can be given as InvalidAgeException
public
class InvalidAgeException extends Exception {} |
public
class InvalidAgeException extends Exception { private int age; public InvalidAgeException () { super(); } public InvalidAgeException (String message, int age) { super(message); this.age = age; } } |
In the above way we can define two constructors of InvalidAgeException with message and without message
Usage of custom Exception:
Below is the program with usage of custom exception.
public class CustomExceptionDemo { private static final Map<Integer, String> employee = new HashMap<>(); static { employee.put(100, "Mahesh"); employee.put(101, "Suresh"); employee.put(102, "Bran"); employee.put(103, "Troy"); } public static void main(String args[]) { CustomExceptionDemo t = new CustomExceptionDemo(); t.getAge(1000); } public String getAge(int age) { if (employee.get(age) == null) { throw new InvalidAgeException ("No such employee exists", age); } return employee.get(name); } } |
SO friends this was my post on Custom Exception .
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