JCEA Part 1: UML

Leo Crawford | Work | JCEA | Part 1 | UML

Syllabus

Although not directly referenced in the Sun syllabus it is an important topic

Information

Building Blocks

Elements

Class
Interface
Collaboration
Use Case
Active Class
Component
Node
Arrow
State Machine
Package
Note

Relationships

There are four types of relationship in UML:

Dependency
Association
Generalization
Relization

1. Dependency

2. Association

An association may have a multiplicity at each end, and representents the number of elements that the element at the far end of the association has of the the clsoe element.

Multiplicity	Meaning
1	One and only one
0..* or *	Zero, One or Many
1..*	One or Many
a..b	Between a and b
a,b	a or b

An association may be directed () or undirected (). If it is undirected then it either means:

it has not been decided if the association is directed
the association is bidirectional

There are two special types of association:

Aggregation
Composition

3. Generalization

Generalization

4. Realization

Realization

Diagrams in UML

Class diagram
Object diagram
Use case diagram
Sequence diagram
Collaboration diagram
Statechart diagram
Activity diagram
Component diagram
Deployment diagram

Common Mechanisms

Specifications
Adornments
Common divisions
Extensibility mechanisms

1. Specifications

The view of a building block may be a part of the whole, e.g. a class may have attributes that are shown in one diagram but not in another.

2. Adornments

Used to represent additional state, e.g. whether a class is abstract, or the visibility of attributes or operations (+public, #protected, -private)

3. Common Divisions

Designates instance of an element. class is an instance of class, :class in an anonymous instance of class and named:class is a named instance of class.

4. Extensibility Mechanisms

Allows UML to be customised and expanded. Tools include:

Steretypes
Tagged values
Constraints

Observations

none

Page created by Leo Crawford
last updated in June 2002