Creating Custom Exceptions in Java: A Practical Guide

Custom exceptions in Java allow you to create specific error types that are more meaningful for your application. You can define your own exception by extending the `Exception` class for checked exceptions or `RuntimeException` for unchecked exceptions.

Here’s how you can create a custom exception:

class InvalidAgeException extends Exception {
    public InvalidAgeException(String message) {
        super(message);
    }
}

public class TestCustomException {
    public static void main(String[] args) {
        try {
            checkAge(15);
        } catch (InvalidAgeException e) {
            System.out.println(e.getMessage());
        }
    }

    static void checkAge(int age) throws InvalidAgeException {
        if (age < 18) {
            throw new InvalidAgeException("Age is not valid");
        }
    }
}
            

This example creates a custom exception `InvalidAgeException` that is thrown when the age is less than 18. Custom exceptions improve code readability and help in handling specific error cases more effectively.