What are some examples of the composite design pattern?

What are some examples of the composite design pattern?

The composite design pattern allows you to compose objects into tree structures to represent part-whole hierarchies. A common example is a graphic system where shapes can be individual objects or compositions of shapes.

Can you give me a code example in Java?

Sure! Here's a simple Java example:

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

interface Component {
    void draw();
}

class Leaf implements Component {
    private String name;

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

    public void draw() {
        System.out.println("Drawing " + name);
    }
}

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

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

    public void draw() {
        for (Component child : children) {
            child.draw();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Composite composite = new Composite();
        composite.add(new Leaf("Circle"));
        composite.add(new Leaf("Square"));

        Composite subComposite = new Composite();
        subComposite.add(new Leaf("Triangle"));
        composite.add(subComposite);

        composite.draw();
    }
}

This code demonstrates how to create a composite structure of shapes.

What are the benefits of using the composite pattern?

The composite pattern simplifies client code by allowing clients to treat individual objects and compositions uniformly. It also promotes flexibility in adding new components.