Object Orientated Design

Question 1

Object Orientation

Answer 1

Organise the software as a collection of discrete objects that incorporate data structure and behaviour.

Question 2

Reusability

Answer 2

Objects, if defined well, are reusable in different situations.

Question 3

Object

Answer 3

Something you can interact with, and behaves differently depending on the state that it is in.
Contains:
- behaviour
- state
- identity

Question 4

Object State

Answer 4

The data which encapsulates it.

Question 5

Object Behaviour

Answer 5

The way an object acts and reacts.

Question 6

Object Interface

Answer 6

An object’s public interface defines which messages it will accept.
Objects may have several interfaces which are viewpoints on the methods provided.

Question 7

Purpose of classes

Answer 7

• Encapsulation
• Convenient way of describing a collection of objects which have same properties
• Classes are used in the same way that types are used in other languages.

Question 8

Inheritance

Answer 8

Sharing attributes and operations among other classes based upon hierarchy.
Composition is normally better.

Question 9

Polymorphism

Answer 9

Allows programmer to use subclasses anywhere that a superclass exists.

Question 10

Dynamic Binding

Answer 10

Objects determines which code to execute as the result of a method call on a base type.

Question 11

UML Uses

Answer 11

• specifying
• visualising
• documenting

Question 12

Noun Analysis

Answer 12

Analyses documentation in terms of nouns, and which ones can be used as classes.
Every noun is a class, but not every class is a noun.
Nouns can either be a class name or an attribute name.