15 Lecture - AGGREGATION

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15 Lecture

CS304

Midterm & Final Term Short Notes

AGGREGATION

Aggregation is a type of association between classes in object-oriented programming where one class contains a collection of another class's objects as a member variable. Unlike composition, the contained objects can exist independently of the c


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  1. What is aggregation in object-oriented programming? a. A type of inheritance b. A way of creating complex objects by combining simpler objects c. A type of association between classes where one class contains a collection of another class's objects Answer: c Can the contained objects in aggregation exist independently of the containing object? a. Yes b. No Answer: a How is aggregation represented in a UML class diagram? a. With a solid line and an arrow pointing to the contained class b. With a dashed line and an arrow pointing to the contained class c. With a dotted line and an arrow pointing to the contained class Answer: b What is the purpose of using aggregation in object-oriented programming? a. To create complex objects by combining simpler objects b. To inherit properties and behaviors from a parent class c. To encapsulate behavior and data Answer: a Can a class have multiple instances of another class as member variables in aggregation? a. Yes b. No Answer: a How does aggregation differ from composition? a. In aggregation, the contained objects cannot exist independently of the containing object b. In composition, the contained objects can exist independently of the containing object c. There is no difference between aggregation and composition Answer: b Can the contained objects be shared among multiple containing objects in aggregation? a. Yes b. No Answer: a What happens to the contained objects when the containing object is destroyed in aggregation? a. The contained objects are automatically destroyed b. The contained objects continue to exist independently of the containing object c. It depends on the implementation Answer: b How does aggregation support code reuse? a. By allowing for the creation of complex objects by combining simpler objects b. By inheriting properties and behaviors from a parent class c. By encapsulating behavior and data Answer: a What are some real-world examples of aggregation? a. A car's engine and transmission b. A house's rooms and furniture c. A human's body parts Answer: b



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Midterm & Finalterm Prepration
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  1. What is aggregation, and how does it differ from composition? Answer: Aggregation is a type of association between classes in object-oriented programming where one class contains a collection of another class's objects as a member variable. Unlike composition, the contained objects can exist independently of the containing object and can be shared among multiple containing objects. Can a class have multiple instances of another class as member variables in aggregation? Answer: Yes, a class can have multiple instances of another class as member variables in aggregation. How does aggregation support code reuse? Answer: Aggregation supports code reuse by allowing for the creation of complex objects by combining simpler objects that can be shared among multiple containing objects. What is the purpose of using aggregation in object-oriented programming? Answer: The purpose of using aggregation is to create complex objects by combining simpler objects that can be shared among multiple containing objects. How is aggregation represented in a UML class diagram? Answer: Aggregation is represented in a UML class diagram with a dashed line and an arrow pointing to the contained class. What happens to the contained objects when the containing object is destroyed in aggregation? Answer: The contained objects continue to exist independently of the containing object in aggregation. Can the contained objects be shared among multiple containing objects in aggregation? Answer: Yes, the contained objects can be shared among multiple containing objects in aggregation. What are some real-world examples of aggregation? Answer: Some real-world examples of aggregation include a house's rooms and furniture, a library's books and shelves, and a computer's peripherals and components. How does aggregation differ from inheritance? Answer: Aggregation is a type of association between classes where one class contains a collection of another class's objects as a member variable, while inheritance is a mechanism that allows a subclass to inherit properties and behaviors from a parent class. What is the benefit of using aggregation over composition? Answer: The benefit of using aggregation over composition is that it allows for greater flexibility and reusability of objects, as the contained objects can exist independently of the containing object and can be shared among multiple containing objects.

Aggregation is a type of association between classes in object-oriented programming where one class contains a collection of another class's objects as a member variable. This relationship is often used to represent "has-a" relationships, where an object of one class "has" or "contains" objects of another class. Unlike composition, which is a stronger form of aggregation, the contained objects in aggregation can exist independently of the containing object and can be shared among multiple containing objects. One of the main benefits of using aggregation is that it allows for greater flexibility and reusability of objects. By creating complex objects through the combination of simpler objects, developers can create more modular and maintainable code. Additionally, the contained objects can be shared among multiple containing objects, which can further reduce duplication of code and improve performance. Aggregation is often represented in UML class diagrams with a dashed line and an arrow pointing to the contained class. The arrow typically indicates the direction of the association, with the arrowhead pointing to the contained class. When a containing object is destroyed, the contained objects continue to exist independently. Real-world examples of aggregation include a house's rooms and furniture, a library's books and shelves, and a computer's peripherals and components. In each of these examples, the containing object (house, library, computer) "has" or "contains" multiple instances of another class (room, book, peripheral) as member variables. While aggregation and composition are both types of association in object-oriented programming, they differ in their strength of relationship. Composition is a stronger form of aggregation where the contained objects cannot exist independently and are owned exclusively by the containing object. In contrast, the contained objects in aggregation can exist independently and be shared among multiple containing objects.

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