Top 3 Composition Interview Questions
Browse 3 real-world technical and behavioral interview questions about Composition. Review scenarios, edge cases, and architectural best practices.
Skip the definitions. Show me encapsulation, abstraction, inheritance and polymorphism, each in about ten lines of code, and then tell me when inheritance is the wrong tool.
OOP examples beat definitions: a class refusing a bad withdrawal shows encapsulation, a caller depending on an interface shows abstraction, a subclass reusing a parent method shows inheritance, and one loop running different overrides shows polymorphism. Inheritance is wrong when the child breaks a parent promise.
Where does encapsulation or polymorphism change a design, and how do you decide between composition and inheritance?
Encapsulation earns its place when a class owns an invariant that callers would otherwise each have to enforce, and polymorphism when a conditional grows with every new requirement. Composition versus inheritance is decided on evidence: how many axes vary, and whether every inherited operation is honest.
When would you use the strategy pattern instead of inheritance?
Use the strategy pattern instead of inheritance when behaviour varies independently from object identity. Composition avoids subclass explosion, enables runtime swapping and makes algorithms easier to test.