A demonstration of Composite Design Pattern

Course Title : Object Oriented Design and Design Patterns Lab(CSE 4122)

Author

Akif Islam
Department of CSE, University of Rajshahi
iamakifislam@gmail.com

Experiment 04

Write a Java program to demonstrate the implementation of a composite design pattern by using an example with a building composed of generic housing structures.

Story of the Program

Though the question asked to implement a generic housing idea with Composite Design Pattern, I accidentally created this program with my own idea of Animal hierarchy. This design pattern follows the basic client-component-leaf model of Composite Design Pattern.

Class Diagram

How to Run?

  $javac CompositePatternDemo.java
  $java CompositePatternDemo

Composite Pattern Demo Program

// Creating Leaf Node for Land Animal
Tiger exampleLandAnimal_1 = new Tiger();
Cat exampleLandAnimal_2 = new Cat();

// Send/Add it to Composite Class -> Land Animal
LandAnimals landAnimals = new LandAnimals();

landAnimals.addAnimal(exampleLandAnimal_1);
landAnimals.addAnimal(exampleLandAnimal_2);
landAnimals.getSubordinates();

// Creating Leaf Node for Water Animal
SilverCarpFish exampleFish = new SilverCarpFish();
WaterAnimals waterAnimals = new WaterAnimals();
waterAnimals.addAnimal(exampleFish);
waterAnimals.getSubordinates();


// Creating Leaf Node for Flying Animal
Parrot exampleFlyingAnimal_1 = new Parrot();
Pigeon exampleFlyingAnimal_2 = new Pigeon();

FlyingAnimals flyingAnimals = new FlyingAnimals();
flyingAnimals.addAnimal(exampleFlyingAnimal_1);
flyingAnimals.addAnimal(exampleFlyingAnimal_2);
flyingAnimals.getSubordinates();

// Send it to Animal Class
Animals animals = new Animals();

animals.addAnimal(landAnimals);
animals.addAnimal(waterAnimals);
animals.addAnimal(flyingAnimals);
animals.getSubordinates();

// Send it to Client Class - God Creature
GodCreatures godCreatures = new GodCreatures();
godCreatures.addAnimal(animals);
godCreatures.getSubordinates();

Output