Custom exception classes in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom exception class in Kotlin?

A custom exception class is a user-defined class that extends the Exception class (or its subclasses) to represent specific error conditions in your program.

beginner

How do you define a simple custom exception class in Kotlin?

You define it by creating a class that inherits from Exception, for example:<br><pre>class MyException(message: String) : Exception(message)</pre>

intermediate

Why create custom exception classes instead of using built-in exceptions?

Custom exceptions help you clearly identify and handle specific error cases in your program, making your code easier to understand and maintain.

beginner

How do you throw a custom exception in Kotlin?

Use the throw keyword followed by an instance of your custom exception, for example:<br>

throw MyException("Something went wrong")

intermediate

Can custom exceptions have additional properties or functions?

Yes, custom exception classes can have extra properties or functions to provide more details about the error or to help with error handling.

Which Kotlin class should you extend to create a custom exception?

A Exception

B String

C Int

D List

Custom exceptions extend the Exception class or its subclasses to represent errors.

How do you throw a custom exception named MyException with a message?

A throw Exception("Error message")

B throw MyException("Error message")

C throw new MyException

D raise MyException("Error message")

In Kotlin, use throw followed by an instance of your custom exception with a message.

What is the benefit of using custom exceptions?

A They automatically fix errors

B They run faster than built-in exceptions

C They prevent all errors

D They make error handling clearer and more specific

Custom exceptions help identify specific errors clearly, improving code readability and maintenance.

Which keyword is used to define a custom exception class in Kotlin?

A class

B fun

C object

D interface

Custom exceptions are defined using the class keyword, extending Exception.

Can a custom exception class have extra properties?

A No, exceptions cannot have properties

B Only if it extends RuntimeException

C Yes, to provide more error details

D Only if it is an interface

Custom exceptions can have additional properties or functions to give more context about the error.

Explain how to create and use a custom exception class in Kotlin.

Think about class inheritance and how exceptions are thrown.

Why might you want to create a custom exception instead of using built-in exceptions?

Consider how custom exceptions help in understanding and managing errors.