UML class diagrams visually represent the structure of a system by showing the system's classes, their attributes, and the relationships between classes. They can show static variables and operations with underlines, associations between classes with lines and arrows to indicate directionality and multiplicity, generalization relationships to represent inheritance, realization relationships to represent interfaces being implemented, and aggregation and composition relationships to represent "has a" relationships between whole and part classes. UML class diagrams provide an overview of the key classes in a system and how they relate and interact.

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Implementation UML Class
Diagrams

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Big questions
 What is UML?
 Why should I bother? Do people really use UML?
 What is a UML class diagram?
 What kind of information goes into it?
 How do I create it?
 When should I create it?

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5.  Representing Static variable or static operation:
The static data is represented with an underline. Let’s
take the below example.
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6.  Association:
The association represents the static relationship
between two classes along with the multiplicity.
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7.  The unidirectional relationship shows that the source
object can invoke methods of the destination class. In
Java a possible example can be the instance variable of
source class referencing the destination class.
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9.  Bidirectional association
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Both use of ArrayList and Array is for
illustration purposes only

12.  Generalization
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13.  Realization:
 This is related to the relationship between the class and
the interface. The realization is equivalent to the
“implements” keyword in Java
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14. Realization
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15. Aggregation
 This shows “has a” relationship. It is a form of
association relationship. This relationship highlights
that a whole is made of its parts. So if a whole is
destroyed the part still remains.
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16. Composition
 This is again a whole or part relationship where if the
whole is destroyed then the part cannot exist
independently. Another important point about
Composition is that the part at any point in time can
have only one owner.
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