Enumerators to iterate through the collections

The .NET Framework introduces Enumerators which can be used to iterate through the collections. Suppose that you have a Group which has SubGroups and each SubGroup has some items. You can iterate the Parent(Group), Child(SubGroup) using Enumerations. Check out the code below:

Group.cs:

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

namespace Something
{
    public class Group : IEnumerable
    {
        private string _name;
        private List<SubGroup> _subGroupList = new List<SubGroup>();

        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public void AddSubGroup(string name)
        {
            SubGroup subGroup = new SubGroup(name);
            _subGroupList.Add(subGroup);
        }

        public int Count
        {
            get { return _subGroupList.Count; }
        }

        public IEnumerator GetEnumerator()
        {
            for (int index = 0; index < Count; index++)
            {
                yield return _subGroupList[index];
            }
        }

    }
}

SubGroup.cs:

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

namespace Something
{
    public class SubGroup : IEnumerable
    {
        private string _name;

        private List<Item> _itemList = new List<Item>();

        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public SubGroup(string name)
        {
            _name = name;
        }

        public void AddItem(string name)
        {
            Item item = new Item(name);
            _itemList.Add(item);
        }

        public int Count
        {
            get { return _itemList.Count; }
        }

        public IEnumerator GetEnumerator()
        {
            for (int index = 0; index < Count; index++)
            {
                yield return _itemList[index];
            }
        }

    }
}

Item.cs:

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

namespace Something
{
    public class Item
    {
        private string _name;

        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public Item(string name)
        {
            _name = name;
        }
    }
}

And now you can iterate over the collections using the following code:

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

namespace Something
{
    class Program
    {
        static void Main(string[] args)
        {
            Group group = new Group();
            group.AddSubGroup("SubGroup1");
            group.AddSubGroup("SubGroup2");

            // Add two new items in each group
            foreach (SubGroup sg in group)
            {
                sg.AddItem("Item1");
                sg.AddItem("Item2");
            }

            foreach (SubGroup subGroup in group)
            {
                Console.WriteLine(subGroup.Name);

                foreach (Item item in subGroup)
                {
                    Console.WriteLine(item.Name);
                }
            }

        }
    }
}

Posted on Saturday, March 18, 2006 10:58 PM | Back to top