SortedList Custom IComparer NullReferenceEx ception

[dcharnigo]

I thought I would be tricky and force the SortedList to not sort using a custom IComparer, I used the following code, but when the list is sorting using the custom sort the accessors become unusable and throw exceptions. I have since discovered that the accessors use the IComparer to find things and since it is set at -1 it gets a null return value, however the foreach loops dont use it. I must preserve the insert order, I don't want the sortinglist to sort, is there any way or type to accomplish this? A ListDictionary does not have the accessors I need. I also need it to be Case-Sensitive meaning for keys I have some that are 'r99' and 'R99' and that they are not the same. (Loading and XML file and XML is Case-Sensitive)

Thanks


Sample Application:

using System;
using System.Collections;
 
namespace Example
{
    // An implementation of IComparer.
    public class Int32ComparerClass : IComparer
    {
        public int Compare(object x, object y)
        {
            // This code assumes neither x and y are null,
            // and they both can be successfully converted to Int32s.
            //return Convert.ToInt32(x) - Convert.ToInt32(y);
            return -1;
        }
    }
 
    public class Test
    {
        [STAThread]
        public static void Main()
        {
            SortedList numericList =
            new SortedList(new Int32ComparerClass());
            numericList.Add("10", "Ten");
            numericList.Add("11", "Eleven");
            numericList.Add("1", "One");
            numericList.Add("2", "Two");
            numericList.Add("3", "Three");
            numericList.Add("0", "0");
            numericList.Add("r99", "r99");
            numericList.Add("R99", "R99");
 
            foreach (DictionaryEntry de in numericList)
                Console.WriteLine(de.Key + ", " + de.Value);
 
            //WILL THROW EXCEPTION
            Console.WriteLine(numericList["1"].ToString());
 
            Console.WriteLine();
 
            SortedList xxx =
                new SortedList();
            xxx.Add("10", "Ten");
            xxx.Add("11", "Eleven");
            xxx.Add("1", "One");
            xxx.Add("2", "Two");
            xxx.Add("3", "Three");
            xxx.Add("0", "0");
            xxx.Add("r99", "r99");
            xxx.Add("R99", "R99");
 
 
            foreach (DictionaryEntry de in xxx)
                Console.WriteLine(de.Key + ", " + de.Value);
 
        //IS OK
        Console.WriteLine(xxx["1"].ToString());
 
        }
    }
}
 

[nukefusion]

Hi, thanks for taking the time out to write a sample program. The code sample you provided should work fine using a ListDictionary. Which accessors are missing from ListDictionary that make it unusable for you?

[dcharnigo]

Thanks, Apparently I wasn't paying attention, it works fine with a list dictionary! Thanks!

[Plater]

I was going to say, you are using a SortedList, but not wanting Sorting and that there must be a better alternative. Glad you found it.