Solved

List<> distinct value

Posted on 2008-06-14
3
10,704 Views
Last Modified: 2013-12-17
I have an object that I call MyObject.  Its parameters are MyObject.Id, MyObject.Name.. etc.
I create a List of this Object.
List<MyObject> myObjectList = new List<MyObject>();
I would like to add to myDistinctList all Objects from myObjectList, except where object exists with the same value in MyObject.Id in myDistinctList.
List<MyObject> myDistinctList = new List<MyObject>();
That is no 2 Objects in myDistinctList may contain the same value in MyObject.Id.
What would be the best way to do this?
0
Comment
Question by:johnkainn
  • 2
3 Comments
 
LVL 1

Accepted Solution

by:
gregmulvihill earned 150 total points
ID: 21786025
If I understand what you are looking for, this should work.  Though, I can't claim this is the 'best way' to achieve your goal, it does seem to be a simplest way that works.
using System;
using System.Collections.Generic;
using System.Text;
 
namespace EE_List_distinct_value
{
	class Program
	{
		private static List<MyObject> myObjectList = new List<MyObject>();
		private static List<MyObject> myDistinctList = new List<MyObject>();
 
		static void Main(string[] args)
		{
			myObjectList.Add(new MyObject("1", "Name_1"));
			myObjectList.Add(new MyObject("4", "Name_4"));
			myObjectList.Add(new MyObject("15", "Name_15"));
 
			AddUnique(myObjectList, myDistinctList);
 
			ShowMyObjects("myObjectList", myObjectList);
			ShowMyObjects("myDistinctList", myDistinctList);
 
			myObjectList.Add(new MyObject("11", "Name_11"));
			myObjectList.Add(new MyObject("15", "Name_15"));
			myObjectList.Add(new MyObject("22", "Name_22"));
 
			AddUnique(myObjectList, myDistinctList);
 
			ShowMyObjects("myObjectList", myObjectList);
			ShowMyObjects("myDistinctList", myDistinctList);
 
			myObjectList.Add(new MyObject("15", "Name_15"));
			myObjectList.Add(new MyObject("13", "Name_13"));
			myObjectList.Add(new MyObject("4", "Name_4"));
 
			AddUnique(myObjectList, myDistinctList);
 
			ShowMyObjects("myObjectList", myObjectList);
			ShowMyObjects("myDistinctList", myDistinctList);
 
			Console.ReadKey();
		}
 
		private static void ShowMyObjects(string ListName, List<MyObject> oMyObjectList)
		{
			Console.WriteLine("MyObject List: " + ListName);
 
			foreach (MyObject oMyObject in oMyObjectList)
			{
				Console.WriteLine(oMyObject);
			}
 
			Console.WriteLine();
		}
 
		private static void AddUnique(List<MyObject> oMyObjectList, List<MyObject> oMyObjectUniqueList)
		{
			foreach(MyObject oMyObject in oMyObjectList)
			{
				if (null == FindMyObjectById(oMyObjectUniqueList, oMyObject.Id)) oMyObjectUniqueList.Add(oMyObject);
			}
		}
 
		private static MyObject FindMyObjectById(List<MyObject> oMyObjectList, string Id)
		{
			foreach (MyObject oMyObject in oMyObjectList)
			{
				if (Id == oMyObject.Id) return oMyObject;
			}
 
			return null;
		}
	}
 
	class MyObject
	{
		public MyObject(string Id, string Name /*,...*/)
		{
			this.Id = Id;
			this.Name = Name;
			//...
		}
 
		public string Id;
		public string Name;
		//...
 
		public override string ToString()
		{
			return string.Format("ID: {0} - Name: {1}", this.Id, this.Name);
		}
	}
}

Open in new window

0
 
LVL 11

Assisted Solution

by:Babycorn-Starfish
Babycorn-Starfish earned 100 total points
ID: 21786506
Hi,

you should override Equals in your 'MyObject' class as follows:

public override bool Equals(object obj)
        {
            return this.ID == ((MyObject)obj).ID;  //if your id is a string use return this.ID.Equals(((MyObject)obj).ID);
        }

then when your adding to the distinct list, use if(!List.Contains(objectToCheck)){List.Add(objectToCheck);}
0
 
LVL 11

Expert Comment

by:Babycorn-Starfish
ID: 21786520
This way when you use the List.Contains method your implementation of Equals will be used
0

Featured Post

DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

A quick way to get a menu to work on our website, is using the Menu control and assign it to a web.sitemap using SiteMapDataSource. Example of web.sitemap file: (CODE) Sample code to add to the page menu: (CODE) Running the application, we wi…
Wouldn’t it be nice if you could test whether an element is contained in an array by using a Contains method just like the one available on List objects? Wouldn’t it be good if you could write code like this? (CODE) In .NET 3.5, this is possible…
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…

785 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question