Aggregation is when one object contains another object, such as how a car contains a steering wheel. In contrast, composition is a more specific form of aggregation. It indicates that one objects owns another object. Follow along with this online programming video to learn about how you can use aggregation and composition to show relational and ownership information among classes.
We've already seen what are referred to as Associations in a diagram.…Drawing any kind of line between objects simply suggests there is some kind of interaction.…One object knows about or interacts with a different object.…We can add a note to explain this, it might just be that one object is calling…a method of another object.…But we can get more specialized with what we're trying to illustrate.…We've seen the way already that we show Inheritance with the empty arrow…pointing at the superclass or parent class.…
And we have another couple of terms here to explore and their supporting diagrams.…We are going to talk about aggregation and composition, both are very long…words for simple ideas.…And they describe an obvious relationship between our objects that one object…can often be built of other objects.…So Aggregation is often referred to as a HAS A relationship as opposed to the…IS A relationship of Inheritance.…We would never say something like a customer is a address, but we might say a…customer has a address or a car has a engine.…
Let Simon Allardice introduce you to the terms—words like abstraction, inheritance, polymorphism, subclass—and guide you through defining your requirements and identifying use cases for your program. The course also covers creating conceptual models of your program with design patterns, class and sequence diagrams, and unified modeling language (UML) tools, and then shows how to convert the diagrams into code.
- Why use object-oriented design (OOD)?
- Pinpointing use cases, actors, and scenarios
- Identifying class responsibilities and relationships
- Creating class diagrams
- Using abstract classes
- Working with inheritance
- Creating advanced UML diagrams
- Understanding object-oriented design principles
Skill Level Intermediate
1. Core Concepts
2. Object-Oriented Analysis and Design
Defining requirements6m 9s
3. Utilizing Use Cases
4. Domain Modeling (Modeling the App)
5. Creating Classes
6. Inheritance and Composition
7. Advanced Concepts
8. Object-Oriented Design Patterns
9. Object-Oriented Design Principles
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