PlantUML Summary

Class Diagrams

Arrows

• Composition (strong ownership)
  • In PlantUML: A *-- B
  • Definition: B objects are created and destroyed at the same time as A.
• Aggregation
  • In PlantUML: A o-- B
  • Definition: B objects may or not may be created and/or destroyed at the same time as A, but this last one keeps them referenced in bulk.
• Association
  • In PlantUML: A --> B
  • Definition: Long time spans in which A will use B. Rule of thumb: A is associated with B and not dependent if it keeps the reference in an attribute for a long time.
• Dependency
  • In PlantUML: A ..> B
  • Definition: Short time spans in which A will use B. It’s the only way of using interfaces. However, it can be used, too, to say A uses objects of B at times, like when returning new objects (in factories) or with a singleton’s getInstance().
• Inner Classes (in-code implementation)
  • In PlantUML: A +-- B
  • Definition: B’s class is defined inside of A’s class rather than in its own file.
• Inheritance (extension)
  • In PlantUML A <|-- B
  • Definition: B inherits all of the attributes and functionalities A has.
  • In code: B extends A.
• Inheritance (implementation)
  • In PlantUML: A <|.. B
  • Definition: A can act as an interface for B, thus B must redefine everything A has.
  • In code: B implements A.

Great Skinparams and Other Configurations

• skin rose: A rosy theme that makes diagrams more beautiful than the default theme.

• hide circle: Make PlantUML class diagrams look like Graphical UML ones!

• skinparam RoundCorner <amount>: Make elements (that support it, like classes) have rounded corners.

• skinparam GroupInheritance <amount>: Group inheritance arrows for multiple elements deriving from the same base.