The document discusses UML class diagrams and their components such as classes, interfaces, attributes, operations, and relationships like generalization, dependency, composition and aggregation. It explains how to represent these components using UML notation including class boxes, association lines, notes, keywords and properties. The document also covers more advanced class diagram topics like templates, compartments and active classes.

1. UML Class Diagrams
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2. What They Are
• They illustrate classes, interfaces, and their
associations. They are used for static object
modeling.
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3. 3

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)
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5. Design Class Diagram
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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.
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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.
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8. UML Attributes
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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
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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.
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11. Collection Attributes
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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
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13. Operations and Methods
• A method is the implementation of an
operation
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14. The Create operation
• This is a constructor call
• You can use <<constructor>> to make this
explicit
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15. Keywords
• A UML keyword is a textual adornment to
categorize a model element
• Keywords include <<actor>>, <<Interface>>,
[abstract], [ordered]
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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
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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}
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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.
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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
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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
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21. Interfaces
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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
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23. Composition
• For example the Monopoly board consists of
40 squares
• A square can be part of only one board at any
time.
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24. Constraints
• Constraints is a restriction on a UML element.
• Shown as text between braces
• {size > 0}
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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
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26. Association Class
• Allows you to treat an association as a class,
such that it can have attributes
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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.
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28. Template Classes and Interfaces
• These are equivalent to C++ or Java
“generics.”
• That is, you can type a collection class.
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29. User-Defined Compartments
• In a class diagram you can define your own
compartments:
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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.
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