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Class Diagram

To be able to generate those diagrams, you must have Graphviz software installed on your machine in the default directory c:\Program Files\GraphvizX.XX or /usr/bin/dot.

You can have a look here if you have installed Graphviz somewhere else.

The description of class diagram is similar to the description of use case diagrams.

New rendering

This page show the rendering given by the new Svek architecture.

Note that you can disable the shadowing using the skinparam shadowing false command.

Relations between classes

Relations between classes are defined using the following symbols :

Extension <|--
Composition *--
Agregation o--

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

Knowing thoses rules, it is possible to draw the following drawings:

@startuml
scale 900 width
Class01 <|-- Class02
Class03 *-- Class04
Class05 o-- Class06
Class07 .. Class08
Class09 -- Class10
Class11 <|.. Class12
Class13 --> Class14
Class15 ..> Class16
Class17 ..|> Class18
Class19 <--* Class20
@enduml
		

Label on relations

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

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

@startuml

Class01 "1" *-- "many" Class02 : contains

Class03 o-- Class04 : agregation

Class05 --> "1" Class06

@enduml
		
You can add an extra arrow pointing at one object showing which object acts on the other object, using < or > at the begin or at the end of the label.
@startuml
class Car

Driver - Car : drives >
Car *- Wheel : have 4 >
Car -- Person : < owns

@enduml
		

Adding methods

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

The system checks for parenthesis to choose between methods and fields.

@startuml
Object <|-- ArrayList

Object : equals()
ArrayList : Object[] elementData
ArrayList : size()

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

Note that the syntax is highly flexible about type/name order.

@startuml
class Dummy {
  String data
  void methods()
}

class Flight {
   flightNumber : Integer
   departureTime : Date
}
@enduml
		

Defining visibility

When you define methods or fields, you can use characters to define the visibility of the corresponding item:

Character Icon for field Icon for method Visibility
- private
# protected
~ package private
+ public
@startuml

class Dummy {
 -field1
 #field2
 ~method1()
 +method2()
}

@enduml
		
You can turn off this feature using the skinparam classAttributeIconSize 0 command :
@startuml
skinparam classAttributeIconSize 0
class Dummy {
 -field1
 #field2
 ~method1()
 +method2()
}

@enduml
		

Abstract and Static

You can define static or abstract methods or fields using the {static} or {abstract} modifier.

These modifiers can be used at the start or at the end of the line. You can also use {classifier} instead of {static}.

@startuml
class Dummy {
  {static} String id
  {abstract} void methods()
}
@enduml
		

Advanced class body

By default, methods and fields are automatically regrouped by PlantUML. You can use separators to define your own way of ordering fields and methods. The following separators are possible : -- .. == __.

You can also use titles within the separators:

@startuml
class Foo1 {
  You can use
  several lines
  ..
  as you want
  and group
  ==
  things together.
  __
  You can have as many groups
  as you want
  --
  End of class
}

class User {
  .. Simple Getter ..
  + getName()
  + getAddress()
  .. Some setter ..
  + setName()
  __ private data __
  int age
  -- crypted --
  String password
}

@enduml
		

Notes and stereotypes

Stereotypes are defined with the class keyword, " << " and " >> ".

You can also define notes using note left of , note right of , note top of , note bottom of keywords.

You can also define a note on the last defined class using note left, note right, note top, note bottom.

A note can be also define alone with the note keywords, then linked to other objects using the .. symbol.

@startuml
class Object << general >>
Object <|--- ArrayList

note top of Object : In java, every class\nextends this one.

note "This is a floating note" as N1
note "This note is connected\nto several objects." as N2
Object .. N2
N2 .. ArrayList

class Foo
note left: On last defined class

@enduml
		

More on notes

It is also possible to use few html tags like :

You can also have a note on several lines

You can also define a note on the last defined class using note left, note right, note top, note bottom.

@startuml

class Foo
note left: On last defined class

note top of Object
  In java, <size:18>every</size> <u>class</u>
  <b>extends</b>
  <i>this</i> one.
end note

note as N1
  This note is <u>also</u>
  <b><color:royalBlue>on several</color>
  <s>words</s> lines
  And this is hosted by <img:sourceforge.jpg>
end note

@enduml
		
It is possible to add a note on a link, just after the link definition, using note on link.

You can also use note left on link, note right on link, note top on link, note bottom on link if you want to change the relative position of the note with the label.

@startuml

class Dummy
Dummy --> Foo : A link
note on link #red: note that is red

Dummy --> Foo2 : Another link
note right on link #blue
	this is my note on right link
	and in blue
end note

@enduml
		

Abstract class and interface

You can declare a class as abstract using "abstract" or "abstract class" keywords.

The class will be printed in italic.

You can use the interface, annotation and enum keywords too.

@startuml

abstract class AbstractList
abstract AbstractCollection
interface List
interface Collection

List <|-- AbstractList
Collection <|-- AbstractCollection

Collection <|- List
AbstractCollection <|- AbstractList
AbstractList <|-- ArrayList

class ArrayList {
  Object[] elementData
  size()
}

enum TimeUnit {
  DAYS
  HOURS
  MINUTES
}

annotation SuppressWarnings

@enduml
		

Using non-letters

If you want to use non-letters in the class (or enum...) display, you can either :
@startuml
class "This is my class" as class1
class class2 as "It works this way too"

class2 *-- "foo/dummy" : use
@enduml
		

Hide attributes, methods...

You can parameterize the display of classes using the hide/show command.

The basic command is: hide empty members. This command will hide attributes or methods if they are empty.

Instead of empty members, you can use:

You can also provide, just after the hide or show keyword: You can use several show/hide commands to define rules and exceptions.
@startuml

class Dummy1 {
  +myMethods()
}

class Dummy2 {
  +hiddenMethod()
}

class Dummy3 <<Serializable>> {
	String name
}

hide members
hide <<Serializable>> circle
show Dummy1 methods
show <<Serializable>> fields

@enduml
		

Hide classes

You can also use the show/hide commands to hide classes.

This may be usefull if you define a large !included file, and if you want to hide come classes after file inclusion.

@startuml

class Foo1
class Foo2

Foo2 *-- Foo1

hide Foo2

@enduml
		

Use generics

You can also use bracket < and > to define generics usage in a class.
@startuml

class Foo<? extends Element> {
  int size()
}
Foo *- Element

@enduml
		

Specific Spot

Usually, a spotted character (C, I, E or A) is used for classes, interface, enum and abstract classes.

But you can define your own spot for a class when you define the stereotype, adding a single character and a color, like in this example:

@startuml

class System << (S,#FF7700) Singleton >>
class Date << (D,orchid) >>
@enduml
		

Packages

You can define a package using the package keyword, and optionally declare a background color for your package (Using a html color code or name).

Note that package definitions can be nested.

@startuml

package "Classic Collections" #DDDDDD {
  Object <|-- ArrayList
}

package net.sourceforge.plantuml {
  Object <|-- Demo1
  Demo1 *- Demo2
}

@enduml
		

Packages style

There are different styles available for packages.

You can specify them either by setting a default style with the command : skinparam packageStyle, or by using a stereotype on the package:

@startuml
package foo1 <<Node>> {
  class Class1
}

package foo2 <<Rect>> {
  class Class2
}

package foo3 <<Folder>> {
  class Class3
}

package foo4 <<Frame>> {
  class Class4
}

package foo5 <<Cloud>> {
  class Class5
}

package foo6 <<Database>> {
  class Class6
}

@enduml
		

You can also define links between packages, like in the following example:
@startuml

skinparam packageStyle rect

package foo1.foo2 {
}

package foo1.foo2.foo3 {
  class Object
}

foo1.foo2 +-- foo1.foo2.foo3

@enduml
		

Namespaces

In packages, the name of a class is the unique identifier of this class. It means that you cannot have two classes with the very same name in different packages.

In that case, you should use namespaces instead of packages.

You can refer to classes from other namespaces by fully qualify them. Classes from the default namespace are qualified with a starting dot.

Note that you don't have to explicitly create namespace : a fully qualified class is automatically put in the right namespace.

@startuml

class BaseClass

namespace net.dummy #DDDDDD {
    .BaseClass <|-- Person
    Meeting o-- Person
    
    .BaseClass <|- Meeting
}

namespace net.foo {
  net.dummy.Person  <|- Person
  .BaseClass <|-- Person

  net.dummy.Meeting o-- Person
}

BaseClass <|-- net.unused.Person

@enduml
		

Automatic namespace creation

You can define another separator (other than the dot) using the command : set namespaceSeparator ???.
@startuml

set namespaceSeparator ::
class X1::X2::foo {
  some info
}

@enduml
		
You can disable automatic package creation using the command set namespaceSeparator none.
@startuml

set namespaceSeparator none
class X1.X2.foo {
  some info
}

@enduml
		

Lollipop interface

You can also define lollipops interface on classes, using the following syntax:
@startuml
class foo
bar ()- foo
@enduml

Changing arrows direction

By default, links between classes have two dashes -- and are verticaly oriented. It is possible to use horizontal link by putting a single dash (or dot) like this:
@startuml
Room o- Studient
Room *-- Chair
@enduml
You can also change directions by reversing the link:
@startuml
Studient -o Room
Chair --* Room
@enduml
It is also possible to change arrow direction by adding left, right, up or down keywords inside the arrow:
@startuml
foo -left-> dummyLeft 
foo -right-> dummyRight 
foo -up-> dummyUp 
foo -down-> dummyDown
@enduml
You can shorten the arrow by using only the first character of the direction (for example, -d- instead of -down-) or the two first characters (-do-).

Please note that you should not abuse this functionnality : GraphViz gives usually good results without tweaking.

Title the diagram

The title keyword is used to put a title.

You can use title and end title keywords for a longer title, as in sequence diagrams.

@startuml

title Simple <b>example</b>\nof title 
Object <|-- ArrayList

@enduml

Legend the diagram

The legend and end legend are keywords is used to put a legend.

You can optionnaly specify to have left, right or center alignment for the legend.

@startuml

Object <|- ArrayList

legend right
  <b>Object</b> and <b>ArrayList</b>
  are simple class
endlegend

@enduml

Association classes

You can define association class after that a relation has been defined between two classes, like in this example:
@startuml
class Student {
  Name
}
Student "0..*" - "1..*" Course
(Student, Course) .. Enrollment

class Enrollment {
  drop()
  cancel()
}
@enduml
You can define it in another direction:
@startuml
class Student {
  Name
}
Student "0..*" -- "1..*" Course
(Student, Course) . Enrollment

class Enrollment {
  drop()
  cancel()
}
@enduml

Skinparam

You can use the skinparam command to change colors and fonts for the drawing.

You can use this command :

@startuml

skinparam class {
	BackgroundColor PaleGreen
	ArrowColor SeaGreen
	BorderColor SpringGreen
}
skinparam stereotypeCBackgroundColor YellowGreen

Class01 "1" *-- "many" Class02 : contains

Class03 o-- Class04 : agregation

@enduml
		

Skinned Stereotypes

You can define specific color and fonts for stereotyped classes.
@startuml

skinparam class {
	BackgroundColor PaleGreen
	ArrowColor SeaGreen
	BorderColor SpringGreen
	BackgroundColor<<Foo>> Wheat
	BorderColor<<Foo>> Tomato
}
skinparam stereotypeCBackgroundColor YellowGreen
skinparam stereotypeCBackgroundColor<< Foo >> DimGray

Class01 << Foo >>
Class01 "1" *-- "many" Class02 : contains

Class03<<Foo>> o-- Class04 : agregation

@enduml
		

Color gradient

It's possible to declare individual color for classes or note using the # notation.
You can use either standard color name or RGB code.

You can also use color gradient in background, with the following syntax: two colors names separated either by:

depending the direction of the gradient. For example, you could have:
@startuml

skinparam backgroundcolor AntiqueWhite/Gold
skinparam classBackgroundColor Wheat|CornflowerBlue

class Foo #red-green
note left of Foo #blue\9932CC {
  this is my
  note on this class
}

package example #GreenYellow/LightGoldenRodYellow {
  class Dummy
}

@enduml
		

Splitting large files

Sometimes, you will get some very large image files.

You can use the "page (hpages)x(vpages)" command to split the generated image into several files :

hpages is a number that indicated the number of horizontal pages, and vpages is a number that indicated the number of vertical pages.

@startuml
' Split into 4 pages
page 2x2

class BaseClass

namespace net.dummy #DDDDDD {
    .BaseClass <|-- Person
    Meeting o-- Person
    
    .BaseClass <|- Meeting

}

namespace net.foo {
  net.dummy.Person  <|- Person
  .BaseClass <|-- Person

  net.dummy.Meeting o-- Person
}

BaseClass <|-- net.unused.Person
@enduml
		

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