Structural UML Modeling
UML Class Diagram Maker
The foundation of object-oriented modeling. Map entity attributes, method signatures, visibility rules, and class relationships.
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What is a UML Class Diagram?
A UML class diagram is a static structural diagram that describes the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among objects.
Class Box Notation
A standard UML class box contains three stacked compartments:
User
- id: string
- email: string
# passwordHash: string
+ validatePassword(pwd: string): boolean
+ updateProfile(name: string): void
Visibility Indicators
+
Public
Accessible by any class
-
Private
Only within this class
#
Protected
Class and subclasses
~
Package
Same package only
Relationships in Class Diagrams
- Association (Solid line): A structural link between two classes.
- Generalization / Inheritance (Solid line + Hollow triangle): Subclass inherits from superclass.
- Realization (Dashed line + Hollow triangle): Class implements an interface contract.
- Aggregation (Solid line + Hollow diamond): "Has-a" relationship with independent lifetimes.
- Composition (Solid line + Filled diamond): "Part-of" relationship where child lifetime depends on parent.