Interfaces, UML, and SOLID Contracts
Read at your own pace. Code execution, quizzes, progress tracking, and the AI tutor are available in the interactive view with JavaScript enabled.
Contracts Between Objects
Interfaces, UML, and SOLID Contracts
In Association, Aggregation, Composition and Casting in OOP, we moved from single classes to relationships between objects: HAS-A, lifecycle ownership, and type casting.
Now we are ready for the next design step:
How do objects agree on what they can ask from each other?
That agreement is called a contract.
In Java, an interface is one of the clearest ways to express a contract. UML gives us a quick visual language for drawing that contract. SOLID principles help us keep the contract stable, small, and useful.
By the end of this lesson, you should be able to look at a low-level design prompt and say: "These classes should not depend on each other directly. They should depend on this interface."
CONTINUE WITH ALGODAILY PREMIUM
Keep going with the complete tutorial.
Unlock the remaining explanations and exercises, alongside the full learning library.
Explore Premium →