The majority of skin parameters will be covered in their own chapter. However, group inheritance has a very specific use for organizing class diagrams. If multiple classes point to the same class the relationship arrow can be merged with the skin parameter groupInheritance followed by a number. By changing the number we can determine the threshold for merging relationships. If the threshold is set to two any entity with two or more relationships with the same trajectory will have those relationships merged.
Example: No Group Inheritance
@startuml
'Example: No Group Inheritance
'Create classes with multiple relationships ranging from one to four relationships.
A1 <|-- B1
A2 <|-- B2
A2 <|-- C2
A3 <|-- B3
A3 <|-- C3
A3 <|-- D3
A4 <|-- B4
A4 <|-- C4
A4 <|-- D4
A4 <|-- E4
@enduml
Example: Group Inheritance Threshold 2
@startuml
'Example: Group Inheritance Threshold 2
'Set the class diagram to merge same trajectory relationships of two or more.
skinparam groupInheritance 2
'Create classes with multiple relationships ranging from one to four relationships.
A1 <|-- B1
A2 <|-- B2
A2 <|-- C2
A3 <|-- B3
A3 <|-- C3
A3 <|-- D3
A4 <|-- B4
A4 <|-- C4
A4 <|-- D4
A4 <|-- E4
@enduml
Example: Group Inheritance Threshold 4
@startuml
'Example: Group Inheritance Threshold 4
'Set the class diagram to merge same trajectory relationships of four or more.
skinparam groupInheritance 4
'Create classes with multiple relationships ranging from one to four relationships.
A1 <|-- B1
A2 <|-- B2
A2 <|-- C2
A3 <|-- B3
A3 <|-- C3
A3 <|-- D3
A4 <|-- B4
A4 <|-- C4
A4 <|-- D4
A4 <|-- E4
@enduml
Packages
Packages are used for organizing classes in the class diagram. It is used for grouping classes together. The most basic package begins with the word "package" followed by the name of the package. Any classes belonging to the package are declared inside the body of the package. The body is defined by a set of curly braces.
Example: Package Declaration
@startuml
'Example: Organization Package Declaration
'Create a basic package with a name.
'Add one class to the package.
package Package1 {
class Class1
}
@enduml
Name
Example: Package Name
@startuml
'Example: Package Name
'Create a basic package with a name.
'Add one class to the package.
'Use creole to emphasize the name.
package "__Package 1__" {
class Class1
}
'Create a basic package with a name.
'Add one class to the package.
'Use markup to add color and emphasis to the name.
package "<color #561D5E><i>Package 2</i></color>" {
class Class2
}
@enduml
Types
The type is set immediately after the name, wrapped in a double set of less than and greater than signs. There are six package types. The default package type is a folder.
Example: Package Types
'Example: Package Types
'Create a package with a name for all six package types.
'Add one class to each package.
package Node <<Node>> {
class Class1
}
package Rectangle <<Rectangle>> {
class Class2
}
package Folder <<Folder>> {
class Class3
}
package Frame <<Frame>> {
class Class4
}
package Cloud <<Cloud>> {
class Class5
}
package Database <<Database>> {
class Class6
}
@enduml
Body Color
The body_color property determines the fill color of the drawn package entity. The body_color is defined by a standard color name or hex code. Create a gradient by using two colors. If you use this property alone it must come after a hash (#) sign and touch the hash sign. If any other properties follow this place a semicolon (;) between them. No spaces are needed.
Example: Package Body Color
@startuml
'Example: Package Body Color
'Create a package with a name and a class.
'Assign a body_color.
package Package1 #009EA1 {
class Class1
}
'Create a package with a name and a class.
'Assign a gradient to body_color.
package Package2 #009EA1/white {
class Class2
}
@enduml
Line Color
The line_color property determines the color of the line that draws the box of the package. The line_color is defined by a standard color name or hex code. Create a gradient by using two colors. If you use this property alone it must come after a hash (#) sign and touch the hash sign. If any other properties follow this place a semicolon (;) between them. No spaces are needed.
Note: Line_color gradients do not perform well on packages. They only affect the line under the package name.
Example: Package Line Color
@startuml
'Example: Package Line Color
'Create a package with a name and a class.
'Assign a line_color.
package Package1 #line:561D5E {
class Class1
}
'Create a package with a name and a class.
'Assign a gradient to line_color.
package Package2 #line:561D5E/white {
class Class2
}
@enduml
Line Style
The line_style property determines the type of line that draws the box of the class. The line_style is defined by one of the three options below. If you use this property alone it must come after a hash (#) sign and touch the hash sign. If any other properties follow this place a semicolon (;) between them. No spaces are needed.
line.dashed
line.dotted
line.bold
Example: Package Line Style
@startuml
'Example: Package Line Style
'Create a package with a name and a class.
'Make the line_style bold.
package Package1 #line.bold {
class Class1
}
'Create a package with a name and a class.
'Make the line_style dashed.
package Package2 #line.dashed {
class Class2
}
'Create a package with a name and a class.
'Make the line_style dotted.
package Package3 #line.dotted {
class Class3
}
@enduml
Body
The body of the package displays the classes that belong to the package. Classes that belong to the package should be written inside the body of the package. Relationships can be written inside or outside of the package body.
Example: Package Body
@startuml
'Example: Package Body
'Create a package with a name and two classes.
'Create a relationship between the classes inside the package.
package PackageA {
class ClassA1
class ClassA2
ClassA1 -- ClassA2
}
'Create a second package with a name and a class.
package PackageB {
class ClassB1
}
'Create a relationship between a class from the first package and a class from the second class.
ClassA1 - ClassB1
@enduml
With All Properties
Example: Packages With All Properties
@startuml
'Example: Packages With All Properties
package __PackageA__ <<Database>> #E6E6E7;line:009EA1;line.dashed {
class ClassA1
class ClassA2
ClassA1 -- ClassA2
}
package "<color #E6E6E7><i>Package B</i></color>" <<Cloud>> #561D5E|191C1F;line:E6E6E7;line.bold {
class ClassB1
}
ClassA1 - ClassB1
@enduml
Namespaces
Namespaces are similar to packages. However, namespaces allow multiple packages to contain classes with the same name. This is not possible with packages. Relationships between classes inside of namespaces must use fully qualified names for the classes in the form of namespace_name.class_name.
Namespaces do not have as many properties as packages.
Example: Namespace Declaration
@startuml
'Example: Namespace Declaration
'Create a namespace with a name and a class.
namespace Home1 {
class Resident
}
'Create a second namespace with a different name and an identically named class.
namespace Home2 {
class Resident
}
'Create a relationship between the two identically named classes.
Home1.Resident - Home2.Resident
@enduml
Name
Example: Namespace Name
@startuml
'Example: Namespace Names
'Create a namespace with a name and a class.
namespace Home1 {
class Resident
}
'Create a second namespace with a different name and an identically named class.
'Use creole to underline the name.
namespace __Home2__ {
class Resident
}
'Create a relationship between the two identically named classes.
Home1.Resident - __Home2__.Resident
@enduml
Body Color
The body_color property determines the fill color of the drawn namespace entity. The body_color is defined by a standard color name or hex code. Create a gradient by using two colors. This property must come after a hash (#) sign and touch the hash sign.
Example: Namespace Body Color
@startuml
'Example: Namespace Body Color
'Create a namespace with a name and a class.
'Add a body_color.
namespace Home1 #E6E6E7{
class Resident
}
'Create a second namespace with a different name and an identically named class.
'Use a gradient for the body color.
namespace Home2 #E6E6E7/561D5E {
class Resident
}
'Create a relationship between the two identically named classes.
Home1.Resident - Home2.Resident
@enduml
Body
The body of the namespace displays the classes that belong to the namespace. Classes that belong to the namespace should be written inside the body of the namespace. Relationships can be written inside or outside of the namespace body.
Example: Namespace Body
@startuml
'Example: Namespace Body
'Create a namespace with a name and two classes.
'Create a relationship between the classes inside the namespace.
namespace Home1 {
class Resident
class Owner
'Create a relationship between both classes in this namespace.
Resident -- Owner
}
'Create a second namespace with a different name and one identically named class.
namespace Home2 {
class Resident
}
'Create a relationship between the two identically named classes.
Home1.Resident - Home2.Resident
@enduml
With All Properties
Example: Namespace With All Properties
@startuml
'Example: Namespace With All Properties
namespace Home1 #E6E6E7{
class Resident
class Owner
Resident -- Owner
}
namespace Home2 #E6E6E7/561D5E{
class Resident
}
Home1.Resident - Home2.Resident
@enduml
Automatic Namespace Creation
You can create namespaces automatically with the namespaceSeparator setting. When activating the setting pick two special characters and those will be your separator. The example below recreates the example from the namespace body property.
To turn off automatic namespace creation set the namespaceSeparator setting to "none".
Note: The namespaceSeparator must be used to identify specific classes now, instead of the default period between namespace and class.
Example: Automatic Namespace Creation
@startuml
'Example: Automatic Namespace Creation
'Designate a namespaceSeparator.
set namespaceSeparator ::
'Create a namespace with two classes.
class Home1::Resident
class Home1::Owner
'Create a relationship between both classes in this namespace.
Home1::Resident -- Home1::Owner
'Create a second namespace with one identically named class.
class Home2::Resident
'Create a relationship between the two identically named classes.
Home1::Resident - Home2::Resident
'Turn off automatic namespace creation.
set namespaceSeparator none
'Try to create another namespace and class similar to the previous namespaces and classes.
class Home3::Resident
@enduml
Visibility
There are three ways to affect the visibility of entities in a class diagram. PlantUML adjusts visibility from the top down. This allows you to hide a large unneeded portion of the diagram and just show what you need.
hide - hides parts of the class diagram, the parts still take up space in the diagram
show - shows a part of a class that might otherwise be hidden
remove - removes parts from the class diagram, they no longer take up space
Example: Visibility Starting Point
Use the following code as the starting point for the rest of the visibility examples.
Note: We will be changing the background color to more easily track the size of the diagram. Skin parameters will be covered in their own section.
You can change the visibility of a class by following the key word with the class name. You can change the visibility of several classes at a time by replacing the class name with a stereotype.
Example: Hiding, Showing, and Removing Classes
Notice how the below code leaves space for Interface2 because it is only hidden. However the part of the diagram containing Class3 is completely removed because we removed Class3.
@startuml
'Example: Hiding Showing and Removing Classes
skinparam BackgroundColor #E6E6E7
class Class1 <<Top>> {
Method_1()
Property_1
}
interface Interface2 <<Top>>
class Class3 {
Method_3()
Property_3
}
enum Enum4
Class1 - Interface2
Class1 -- Class3
'Hide all <<Top> stereotypes.
hide <<Top>>
'Unhide or show Class1.
show Class1
'Remove Class3.
remove Class3
@enduml
Hiding and Showing Parts of Classes
You can adjust visibility on parts of classes by placing their property type after the visibility keyword. The following items are adjustable. You can be specify which class to adjust if you place the name or stereotype of the class before the property type.
members - this will adjust visibility of all fields, attributes and methods
fields or attributes - this will adjust visibility of all fields and attributes
methods - this will adjust visibility of all methods
circle - this will adjust the visibility of spots in the class heads
stereotype - this will adjust the visibility of stereotypes in the class head
Example: Hiding and Showing Parts of Classes
@startuml
'Example: Hiding and Showing Parts of Classes
skinparam BackgroundColor #E6E6E7
class Class1 <<Top>> {
Method_1()
Property_1
}
interface Interface2 <<Top>>
class Class3 {
Method_3()
Property_3
}
enum Enum4
Class1 - Interface2
Class1 -- Class3
'Hide all fields, attributes, and methods.
hide members
'Hide the spots in all "Top" stereotypes.
hide <<Top>> circle
'Show the methods for Class1.
show Class1 methods
@enduml
Hiding and Removing Empty and Unlinked Entities
By adding the keywords "empty" and "@unlinked" you can hide or remove unneeded entities from the class diagram.
Example: Empty and Unlinked Entities
@startuml
'Example: Empty and Unlinked Entities
skinparam BackgroundColor #E6E6E7
class Class1 <<Top>> {
Method_1()
Property_1
}
interface Interface2 <<Top>>
class Class3 {
Method_3()
Property_3
}
enum Enum4
Class1 - Interface2
Class1 -- Class3
'Hide all empty fields, attributes, and methods.
hide empty members
'Remove all classes that do not have any relationships.
remove @unlinked
@enduml
Positioning Classes With Hidden Relationships
Example: Class Positioned With Hidden Relationship
@startuml
'Example: Class Positioned With Hidden Relationship
skinparam BackgroundColor #E6E6E7
class Class1 <<Top>> {
Method_1()
Property_1
}
interface Interface2 <<Top>>
class Class3 {
Method_3()
Property_3
}
enum Enum4
Class1 - Interface2
Class1 -- Class3
'Use a hidden relationship to place Enum4 under Interface2.
Interface2 -[hidden]- Enum4
@enduml
Page Breaks
If you need to split a diagram into multiple pages use the command "page" followed by the number of pages you want. The page number format is HxV where H is the number of pages horizontally and V is the number of pages vertically.
When the images are generated they will be created from top to bottom and then left to right. A "page 3x2" named "Diagram" will produce six images with the below names that should be placed in the below order.
Diagram
Diagram_2
Diagram_4
Diagram_1
Diagram_3
Diagram_5
Example: Page Breaks 3x2
@startuml
'Example: Page Breaks 3x2
skinparam BackgroundColor #E6E6E7
class Class1 <<Top>> {
Method_1()
Property_1
}
interface Interface2 <<Top>>
class Class3 {
Method_3()
Property_3
}
enum Enum4
Class1 - Interface2
Class1 -- Class3
'Break the diagram into three columns and two rows.
page 3x2
@enduml
The name is text that appears in the head of the package. The name can be a single word without quotation marks or it can be a string with quotation marks. Single word supports creole syntax for emphasis. The string method supports emphasis with creole and markup language. The string method also supports colors with markup language. You can define colors with a standard color name or hex code. See for a list of creole and markup options.
The name is text that appears in the head of the package. The name must be a single word without spaces or special characters other than creole characters for underlining. Single word supports creole syntax for underlining however those creole characters are officially part of the name. See for a list of creole.
You can hide relationships with the key word "hidden". In the example Enum4 sticks out to the right. This makes the diagram wider than is needed. You can manually move it under Interface2 by creating a relationship between them and then hiding the relationship.
