Composite design pattern

In software engineering, the composite pattern comes under the structural design pattern. According to this pattern, a group of objects of the same type are treated as a single object by the client. The idea behind the Composite design pattern is to compose a set of objects into a tree structure to represent a module of a larger structural application. And this structure for clients is a single unit or instance uniformly.

The motivation behind the Composite design pattern is that objects in the system are grouped into the tree structure, and a tree structure is a combination of the node-leaf and branches. In the tree structure, nodes have a number of leaves and other nodes. Leaf doesn't have anything, which means there is no child of leaf in the tree. Leaf is treated as the end point of tree-structured data.

Let's look at the following figure, which represents data in the tree structure in the form of node and leaf: