🌳 Composite Design Pattern — Java LLD + UML + Real Use Cases

The Composite Pattern is a structural design pattern that allows clients to treat individual objects and groups of objects uniformly. It is commonly used to build tree structures, such as filesystems, UIs, and org charts, and enables recursive structures using "has-a" relationships. The pattern is useful in scenarios where clients need to treat leaf nodes and composite nodes uniformly via a shared interface. In a Composite Pattern, individual objects and compositions are treated uniformly, enabling recursive composition and hierarchical navigation. The pattern is beneficial as it provides uniformity, recursive composition, and follows the Open/Closed Principle. However, it can make code harder to understand if overused, and requires careful traversal to avoid performance hits on large trees. The Composite Pattern is ideal for modeling tree-like hierarchies, such as file systems, menus, UI trees, and org charts. In Java, examples of the Composite Pattern can be found in java.awt.Component and javax.swing.JComponent. The pattern is useful when the problem domain requires recursive traversal or group-leaf relationships, and follows the Composite Principle of treating individual objects and composites uniformly. By using the Composite Pattern, clients can treat individual objects and groups of objects the same way, enabling flexible and nested structures.