Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.

Use the Composite pattern when

• you want to represent part-whole hierarchies of objects
• you want clients to be able to ignore the difference between compositions of objects and individual objects. Clients will treat all objects in the composite structure uniformly

• java.awt.Container and java.awt.Component
• Apache Wicket component tree, see Component and MarkupContainer

• Design Patterns: Elements of Reusable Object-Oriented Software