1. What is UML?
A modeling language standardized by the OMG (Object Management Group), and widely used in OO analysis and design
A modeling language is a visual language for representing software blueprints
Latest version is 2.0
UML provides a standard notation, semantics for a set of OO abstractions
CS 3500

2. UML Overview UML defines a visual representation of a concept
Everything that is defined in this has meaning
Just like when writing code, you use () or , or + to represent something
Same is true in UML
So, be careful of the types of arrows, boxes, etc. that you use
Be careful of where you put other symbols
Remember that there is a REAL syntax defined for UML
You can’t just write/draw whatever you like
Our focus – reading UML Class diagrams
Next semester, writing them and other diagrams
CS 3500

3. UML Class Class name Data members (attributes) Instance methods
These compartments are optional. But if you need methods, then you have to have at least empty data member compartment.
Instance methods
Class method (static)
Return types
Arguments
Important – if something isn’t specified, then that doesn’t necessarily mean
that it isn’t there. For example, does name take an argument or not, does it
return a value?
CS 3500

4. visibility name : type multiplicity = default {property-string}
Class Attributes
Attributes are the instance
and class data members
Class data members (underlined)
are shared between all instances
(objects) of a given class
(think static).
Data types shown after ":"
Visibility shown as
+ public
- private
# protected
Attribute
compartment
Attribute Model
visibility name : type multiplicity = default {property-string}
CS 3500

5. visibility name (parameter-list) : return-type {property-string}
Class Operations
Operations are the class
methods with their argument
and return types
Public (+) operations define the
class interface
Class methods (underlined)
have only access to class data
members, no need for a class
instance (object)
Parameter List –
direction name: type = default
Direction Model –
direction – in, out, inout
Operations
compartment
Operations Model
visibility name (parameter-list) : return-type {property-string}
CS 3500

6. Multiplicity - 1 Indicates how many objects may fill the property
1 – exactly one
– may or may not have one
* – zero or more
n .. m – from n to m where n < m
Default is [1]
But it is best to not use default even if value is 1 to make it clear
Question – if you indicate that something is a n..m multiplicity, then how is this realized?
CS 3500

7. Unary Association A knows about B, but B knows nothing about A
UML Comment
These two
diagrams
are identical
in what they
mean.
Arrow shows direction of
association in direction of
dependency
CS 3500

8. Unary Association IS an Attribute
Exactly the same as an attribute
Did you hear me? Exactly the same!!!
Solid line (source to target)
Name goes at the target end, plus multiplicity
It is WRONG to include both an association and a attribute of the same thing
That implies that BOTH exist at the same time
What is the difference between a unary association (line) and an attribute?
IT IS THE SAME THING!!!!! Don’t forget!!!!
CS 3500

9. Binary Association Binary association: both classes know each other
Usually "knows about" means a pointer or reference
Other methods possible: method argument, tables, database, ...
Implies dependency cycle
CS 3500

10. Dependency Weak relationships (also transitory):
Class A simply knows of class B
E.g., a method in A creates and immediately returns an object of class B
That is: a change in one may force changes in the other although there is no explicit association between them.
CS 3500

11. Generalization (Inheritance)
Base class or super class
Arrow shows direction
of dependency
Derived class or subclass
CS 3500

12. Aggregation Aggregation = Association with "whole-part" relationship
Shown by hollow diamond
at the "whole" side
No lifetime control implied
CS 3500

13. Composition Composition = Aggregation with lifetime control
Shown by filled diamond
at the "owner" side
Lifetime control implied
Lifetime control can be
transferred
Lifetime control: construction and
destruction controlled by "owner"
→ call constructors and destructors
(or have somebody else do it)
CS 3500

14. Composition/Aggregation Notations
whole
part
composition
aggregation
part
CS 3500

15. Describe This Diagram
CS 3500