Composite Pattern Demo : Composite Pattern : Design Patterns C# Source Code

    
 
using System;
using System.Text;
using System.Collections;

public abstract class Unit {
    protected string name;
    public abstract void Add(Unit e);
    public abstract void Remove(Unit e);
    public abstract void GetChild(int level);

    public Unit(string name) {
        this.name = name;
    }
}


public class Office : Unit {
    public override void Add(Unit c) {
        Console.WriteLine("Can't use 'Add' in Office!");
    }

    public override void Remove(Unit e) {
        Console.WriteLine("Can't use 'Remove' in Office! ");
    }

    public override void GetChild(int level) {
        Console.WriteLine(new string('*', level) + this.name);
    }

    public Office(string name) : base(name) {}
}


public class Branch : Unit {
    private ArrayList node = new ArrayList();

    public override void Add(Unit e) {
        node.Add(e);
    }

    public override void Remove(Unit e) {
        node.Remove(e);
    }

    public override void GetChild(int level) {
        Console.WriteLine(new String('#', level) + this.name);
        foreach (Unit e in this.node)
            e.GetChild(level + 1);

    }

    public Branch(string name) : base(name) {}
}

public class Client {
    static void Main(string[] args) {
        Branch root = new Branch("US (Root)");
        Office ny = new Office("A (Unit)");
        Office ca = new Office("B (Unit)");

        root.Add(ny);
        root.Add(ca);

        Branch rootHawaii = new Branch("Canada Branch (Branch)");
        root.Add(rootHawaii);

        Branch branchUK = new Branch("UK Branch (Branch)");
        Office ldnc = new Office("C Office (Unit)");
        Office ldnw = new Office("D Office (Unit)");
        branchUK.Add(ldnc);
        branchUK.Add(ldnw);
        root.Add(branchUK);

        Office dummy = new Office("D Office");
        ldnc.Add(dummy);

        root.GetChild(0);

        root.Remove(rootHawaii);
        branchUK.Remove(ldnc);
        Console.WriteLine("Remove Hawaii branch and London City office");
        root.GetChild(0);
    }
}