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Class Diagram

Experiment syntax may change.

A class diagram in the Unified Modeling Language (UML) is a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among objects. Wikipedia

A simple demo​

classDiagram

  class Fruit {
    float sweetness
    -float age

    float getAge()
  }

  class Apple {
  }

  Fruit <|-- Apple
  Fruit <|-- Kiwi

  Container "1" *-- "many" Fruit : holds

Define a class​

Class members​

To declare fields and methods, you can use the symbol : followed by the field's or method's name.

It is also possible to group between brackets {} all fields and methods.

You can write type and name in any order you prefer.

classDiagram
  class Fruit {
    float sweetness

    squeeze()
  }

  Fruit : getAge(): float

Member visibility​

Define member visibility with these symbols. The notaiton is optional but it should be placed before the member.

  • + public
  • # protected
  • - private
  • ~ package/internal

Relations between classes​

You can define relations between classes using following symbols :

TypeDescription
<|--Inheritance
*--Composition
o--Aggregation
-->Association
--Link

It is possible to replace -- by .. to have a dotted line.

classDiagram
classA <|-- classB
classC *-- classD
classE o-- classF
classG <-- classH
classI -- classJ
classK <.. classL
classM <|.. classN
classO .. classP

Label on relations​

It is possible to add a label on the relation, using :, followed by the text of the label.

Also, you can use double-quotes "" on each side of the relation for cardinality.

classDiagram
  classA "1" *-- "many" classB : contains
  classC o-- classD : aggregation
  classE --> "1" classF