The Composite Pattern is a structural design pattern that allows you to compose objects into tree-like structures to represent part-whole hierarchies

· The Component interface declares the operation method.

· The Leaf class represents the leaf nodes, implementing the Component interface.

· The Composite class represents the composite nodes, managing their children and implementing the Component interface.

· The Client class demonstrates how the composite pattern can be used to create complex structures and perform operations on them.

package com.govtech.viswa.designpatterns.composite;

import java.util.ArrayList;
import java.util.List;

/**
 * @author Sarav on 07 May 2024
 * @project govtech
 * @package com.govtech.viswa.designpatterns.composite
 * @class Composite
 */

// Component
interface Component {
void operation();
}

// Leaf
class Leaf implements Component {
private String name;

public Leaf(String name) {
this.name = name;
    }

@Override
public void operation() {
System.out.println("Leaf: " + name + " - Operation performed");
    }
}

// Composite
public class Composite implements Component {
private List<Component> children = new ArrayList<>();

public void add(Component component) {
children.add(component);
    }

public void remove(Component component) {
children.remove(component);
    }

@Override
public void operation() {
System.out.println("Composite - Operation performed");
for (Component component : children) {
component.operation();
        }
    }
}

// Client
class Client {
public static void main(String[] args) {
// Create leaf nodes
Leaf leaf1 = new Leaf("Leaf 1");
Leaf leaf2 = new Leaf("Leaf 2");
Leaf leaf3 = new Leaf("Leaf 3");

// Create composite node and add leaf nodes
Composite composite = new Composite();
composite.add(leaf1);
composite.add(leaf2);

// Create another composite node and add leaf and composite nodes
Composite composite2 = new Composite();
composite2.add(leaf3);
composite2.add(composite); // Adding a composite node as a child

        // Perform operation on composite node
composite2.operation();
    }
}

Composite - Operation performed

Leaf: Leaf 3 - Operation performed

Composite - Operation performed

Leaf: Leaf 1 - Operation performed

Leaf: Leaf 2 - Operation performed