What are some examples of custom exceptions in programming?

What are some examples of custom exceptions in programming?

Custom exceptions are user-defined exceptions that extend the base exception class. For example, in Python, you might create a ValidationError for input validation issues.

Can you show me how to implement a custom exception in Python?

Sure! Here's a simple implementation:

class ValidationError(Exception):
    pass

def validate_age(age):
    if age < 0:
        raise ValidationError('Age cannot be negative.')

This code defines a ValidationError and raises it if the age is invalid.

What about in Java? Can you give me an example?

Absolutely! In Java, you can create a custom exception like this:

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

// Usage
throw new ValidationException("Invalid input!");

Are there any best practices for creating custom exceptions?

Yes, some best practices include: naming your exceptions clearly, extending from the appropriate base exception, and providing useful error messages.