IS Chapter 4
1. Which of the following best describes an object?
A concept, abstraction or thing in an application domain.
11. Which of the following best describes a type?
A description of a set of objects with similar behaviours.
10. What is generalization?
A kind of relationship between a more general element and a more specific element.
17. What is a message protocol or signature?
A message protocol is the interface to an operation.
2. Which of the following best describes abstraction?
A representation that contains only relevant details.
8. Which of the following is not a description of a class?
A set of objects that collaborate together to achieve some common objective.
14. Which of the following is not a characteristic of a subclass?
A subclass can only have superclasses, it cannot have superclasses of its own.
15. What is meant by 'transitive operation' in the context of generalization and inheritance?
A subclass inherits characteristics from all its superclasses at all levels.
19. Which of the following best describes encapsulation?
Data within an object can only be accessed by passing a valid message to one of its own operations.
12. Which of the following is not an advantage of generalization?
Generalization helps to encapsulate classes and subsystems so that their implementation is hidden from other parts of the system.
22. Which of the following is a valid reason why it is difficult to design event-driven software in a procedural manner?
It is difficult to anticipate and design for all possible sequences of use
23. Which of the following is not an advantage of modular software design?
Modular system are independent of the operating system that they run on.
18. What is meant by multiple inheritance?
Multiple inheritance signifies that a class simultaneously belongs to more than one generalization hierarchy.
16. What is the significance of message-passing in an OO system?
Objects exchange messages in order to communicate with each other.
4. What do all objects have?
State, behaviour and identity.
21. WHich of the following best describes polymorphism?
The capacity of an object to send different messages to different objects according to their class.
20. Which of the following best describes an object's interface?
The complete set of signatures for all the object's operations.
5. Which of the following best describes object state?
The particular condition that an object is in at a given moment, determining its possible behaviours.
9. Which of the following best describes the relationship between an object and its class?
The structure and permitted behaviours of an object are defined by its class.
3. Which of the following is not a reason for modelling objects?
To separate data from process.
6. Which of the following best describes object behaviour?
What the object is able to do for other objects.
7. Which of the following is a useful set of questions to ask when modelling an object, according to Rebecca Wirfs-Brock?
Who am I, what can I do and what do I know?
13. How does generalization differ from inheritance?
With generalization each class has only one superclass, whereas with inheritance each class has two or more superclasses.
