Stage 2 · Lesson 3 of 8
Inheritance and when not to use it
lets a new class, called a subclass, reuse and extend a parent class. A SavingsAccount is an Account that also earns interest. Inheritance fits genuine "is a" relationships, and code written for the parent then works with any subclass.
It is also the most overused feature. In a deep chain of classes, each subclass depends on the inner details of its parents. A change at the top can break classes far below.
And a subclass that cannot keep every promise its parent makes causes subtle bugs. Learn this rule: a subclass must work anywhere the parent is expected. You will meet it again as the .
Common trapusing inheritance just to share code between classes that are not really the same kind of thing.
A question to check yourself, an AI practice session and 1 cheat sheet entry come with the full roadmap. Unlock
Resources for this stage
Start with· follow one of these
- CoursePaidGrokking SOLID Design Principles
Design Gurus · Beginner · $50 one-time
Each SOLID principle with a broken example and its fix, at a beginner-friendly pace
- CourseFreeJava Programming MOOC
University of Helsinki · Beginner
Free, exercise-heavy course whose second half is a thorough, tested introduction to OOP