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Object-Oriented Programming · Module 7 of 10

Composition and relationships

Model "has-a" relationships between objects.

📖 Key ideas

  1. Composition: an object contains other objects (Car has an Engine).
  2. Aggregation: weaker has-a; parts can exist alone.
  3. Association: objects use each other.
  4. "Favour composition over inheritance" for flexibility.
  5. UML class diagrams show these relationships.
💡 Real-life example: Composition is building a computer from parts: CPU, RAM, disk, each a separate object.
CompositionStrong has-a; parts owned by whole
AggregationWeak has-a relationship
AssociationObjects linked or using each other
Has-aContains relationship