UML Class Diagrams

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Design class diagrams 🔗

The same UML class-diagram notation can be used from different perspectives.

Conceptual perspective: A
domain model
.
Design perspective: A
design class diagram
.

Associations from different perspectives 🔗

Domain model

Show association names, but avoid navigability arrows because a domain model is not a software perspective.
- Association names are often omitted in domain models, although showing them is valid.
- When using class diagrams from a software perspective, include association names in the DCD.

DCD

Follows the UML specification.

Keywords 🔗

Use keywords to categorize model elements.

For example, use the «actor» keyword in a use case diagram to replace a human stick-figure actor icon with a class box when modeling a computer-system or robot actor.

Keyword	Meaning	Example Usage
«actor»	Indicates that the classifier is an actor	Shown above the classifier name in a class diagram
«interface»	Indicates that the classifier is an interface	Shown above the classifier name in a class diagram
{abstract}	An abstract element that cannot be instantiated	Shown after a classifier or operation name in a class diagram
{ordered}	An object collection has a defined order	Shown at an association end in a class diagram

Stereotypes, profiles, and tags 🔗

Stereotype

: Represents a refinement of an existing modeling concept.

UML stereotypes are defined in the UML specification and are not keywords.
They provide an extension mechanism in UML.

Profile

: A collection of stereotypes,

The relationship between interaction and class diagrams 🔗

Class-diagram definitions can be derived from interaction diagrams.

Drawing an interaction diagram reveals a set of classes and methods.
For example, starting with a makePayment sequence diagram lets you derive definitions for the Register and Sale classes.
Messages in an interaction diagram represent operations in a class diagram.
Classes identified in the interaction diagram are declared in the class diagram.

Deriving code from an interaction diagram 🔗

A sends a doA() message to object X.
Object X creates object Y (create()), and Y sends a doB(this) message to X.
X creates another Y (create()), then sends doD(y2) to the newly created Y.
Finally, X sends a doE() message to Y.

예시 코드

public class X {
    public void doA() {
        Y y1 = new Y();
        boolean flag = y1.doB(this);
        Y y2 = new Y();
        this.doD(y2);
        y2.doE();
    }
    public void doD(Y y) {
        // doD 메소드의 구현
    }
}
 
public class Y {
    public boolean doB(X x) {
        Y y2 = new Y();
        x.doD(y2);
        // ...
        return true; // 예시 값
    }
    public void doE() {
        // doE 메소드의 구현
    }
}
 
public class Main {
    public static void main(String[] args) {
        X x = new X();
        x.doA();
    }
}

UML Class Diagrams | PromleeBlog