Composite design pattern is a way of composing objects into a tree structure representing each in hierarchical form between related objects. The treatment of each group could be in two ways – Composite or Leaf. Composite meaning there can be other objects under it and Leaf, which means that no other objects below it and represents the “primitive” class.
Design patterns provide solutions to certain problems faced in software development. As such, learning these patterns guides developers in learning software design faster.
Here are the basic how to’s in effectively utilizing composite design Pattern in Java:
First, you have to define your Component. Component will state the interface for objects and specifies the default behavior that should be followed uniformly by all the objects composing the structure.
Next, you must classify your subclass, which will be the Primitive and Composite Classes out of the component class.
Below in an example of a structure that contains components, each of these could be a composite.
In a composite design pattern, the leaf class and the composite class shares an interface which defines a common operations which can interchangeably be performed by the leaves and composites. In an instance when an operation on a certain composite is performed, this is performed on all of the composites composing the component; whether they be a leaf or a composite. Thus, this design pattern could be utilized to perform operations which are common on the objects that compose the tree.
The Gang of Four is a description in the composite pattern which states a client’s interaction with the tree through a component interface, wherein this interface could be composed of the common operations on the leaf classes and composite classes, as well as the add/remove/get operations on the composites design structure.
To interact with objects in the composition structure, a client make use of the component class interface in such a way that if the recipient is a leaf then requests are handled directly. If the recipient is a composite, it usually passes this request to the component classes below it, performing further operations before and after forwarding.
The three basic processes in doing composite design would be:
- You have to create your component interface first. This would represent the objects in your composition.
- Next, create you composite class.
- And then, do your developer class, which is a leaf node. Which means that all operations related to accessing below it would be empty.
To be able to direct you on the step by step implementation of doing your composite design pattern.
