Class Diagrams

Question 1

how is a class shown on a class diagram and what does a good class consist of?

Answer 1

a rectangle with a name
it shows the classes in a system, attributes and operations of each class and the relationship between each class.

Question 2

how to avoid conflicts when choosing class names

Answer 2

use a data dictonary

Question 3

what is Data driven design

Answer 3

identify all data in classes and divide it into classes. Then assign methods to these classes.

Question 4

what is responsiblity driven design

Answer 4

idenfify all the reponsibilites(methods) of the systems and divde them into classes.

Question 5

classes correspound to nouns so associations correspone to?

Answer 5

verbs

Question 6

what is an association

Answer 6

a way of expressing a relationship between classes. There are instances of association.

Question 7

What are instances of associations called in UML

Answer 7

links

Question 8

if class A and B are associated then?

Answer 8

some object of class A has to know about some object of class B.

Question 9

Give examples of multiplicities

Answer 9

1 is just 1

1. .10… a range of numbers between 1 and 10
   * - arbitary unspecified number (1..*).. this is 1 to an unknown number

Question 10

what do attributes of a class describe

Answer 10

data contained in an object of the class and their type

Question 11

what do the operations in a class define

Answer 11

the ways in which objects may interact.

Question 12

what is an operation signature

Answer 12

gives the selector, names, types of all formal parameters and return type.

Question 13

what is generalization

Answer 13

if class A is a generalization of class B then the interface of class B must conform to the interface of class A

Question 14

does generalization increase the coupling of a system?

Answer 14

yes

Question 15

difference between generalization and inheritance

Answer 15

generalization is a conceptual relationship whereas inheritance is an implementation relationship

Question 16

What is CRC and what is it good for

Answer 16

Classes, Responsibilities and Collaborations and is used for checking good design. Not part of UML.

Question 17

What does a CRC consist of

Answer 17

Name of class on top
responsiblities of class on the left
collaborators on the right

Question 18

Too many responsibilities in a CRC means what?

Answer 18

low cohesion (bad level abstraction)

Question 19

what does too many collaborators mean in a CRC?

Answer 19

high coupling (class is connected to too many other classes).

Question 20

What is the compromise between coupling and cohesion

Answer 20

high cohesion and low coupling