4. Design Class Diagram
• A class diagram can be used to visualize a
domain model. We also need a unique term to
clarify when the class diagram is used in a
software or design perspective. A common
modeling term for this purpose is design class
diagram (DCD)
4
6. Classifier
• A UML classifier is “a model element that
describes behavioral and structure features”.
Classifiers can also be specialized. They are a
generalization of many of the elements of the
UML, including classes, interfaces, use cases,
and actors. In class diagrams, the two most
common classifiers are regular classes and
interfaces.
6
7. Showing UML Attributes
• Attribute text notation such as: currentSale :
Sale, Association line notation, or both
• <visibility> name : type multiplicity = default
{property string}
• Attributes are assumed private if no visibility
is given
• Arrow shows that the object where the arrow
starts has one object of the object to which it
points.
7
9. UML Attributes
• Multiplicity shows how many on the left can
associate with how many on the right
• Role name
• Attributes are assumed private unless
otherwise noted
9
10. Attribute Text vs. Association Lines
• Use text notation for primitive data types,
even things like Zip codes that may have
components but are not complex
• Use association for everything else.
10
12. Note Symbols
• A UML note symbol is displayed as a dog-eared
rectangle with a dashed line to the annotated
element; they’ve already been used throughout
the book. A note symbol may represent several
things, such as:
– a UML note or comment, which by definition have no
semantic impact
– a UML constraint, in which case it must be encased in
braces ‘{…}’
– a method body—the implementation of a UML
operation
12
14. The Create operation
• This is a constructor call
• You can use <<constructor>> to make this
explicit
14
15. Keywords
• A UML keyword is a textual adornment to
categorize a model element
• Keywords include <<actor>>, <<Interface>>,
[abstract], [ordered]
15
16. Stereotypes, Profiles, Tags
• Stereotypes are also shown in guillemets
symbols . They are not keywords. A
stereotype represents a refinement to an
existing modeling concept
16
17. Properties and Property Strings
• A property is “a named value denoting a
characteristic of an element
• Textual approach is to use the UML property
string {name1=value1, name2=value2} format,
such as {abstract, visibility=public}
17
18. Generalization
• A taxonomic relationship between a more
general classifier and a more specific classifier
• This can imply inheritance, but not at the
conceptual level.
18
19. Dependency
• Similar to association. Indicates that a client
element has knowledge of another supplier element,
and a change in the supplier could affect the client
• (Supplier and client are descriptive terms, not
classes)
• Dependency lines are common on class and package
diagrams
• Use to depict global, parameter variable, local
variable, and static-method dependency
19
20. Types of Dependency
• Having an attribute of supplier type
• Send a message to a supplier
• Receiving a parameter of supplier type
• Supplier is a superclass or interface
• Indicated by a dashed line arrow
20
22. Composition Vs. Aggregation
• Aggregation is a vague association suggesting
whole-part relationships. No meaningful
semantics in UML versus association.
• Composition, or composite aggregation, is a
strong kind of whole-part relationship.
• Implies that an instance of the part belongs to
only one composite instance of the whole
22
23. Composition
• For example the Monopoly board consists of
40 squares
• A square can be part of only one board at any
time.
23
25. Qualified Association
• Uses a qualifier to select an object or set of
objects from a larger set
• For example, looking up something in a
HashMap
25
27. Singleton Class
• Only one instance of a Singleton class (pattern
explained later) is ever instantiated.
• For example, your main class in most
programs is a Singleton, although this may not
be its dominant pattern.
27
28. Template Classes and Interfaces
• These are equivalent to C++ or Java
“generics.”
• That is, you can type a collection class.
28
29. User-Defined Compartments
• In a class diagram you can define your own
compartments:
29
DataAccessObject
Id: int
doX();
Exceptions thrown
DatabaseException
IOExeception
Responsibilities
Serialize and write objects
Read and deserialize objects
30. Active Class
• An active object runs on and controls its own
thread of execution
• In UML, it is shown with double vertical lines
on the left and right of the class box.
30
