How do I sort items within an ArrayList or GenericList using custom compare and sort criteria?

I wanted to find out if there is a way to sort an ArrayList or Generic List (either will work) by different criteria within the same list using either Linq or ICompare type code.

Example:  Imagine that someone wants to display a list of people in a sort order that can take two criteria into account when doing the sort, like an explicit integer based sort order then a default fall-back order for any items that do not have an explicit ordering.

If you have a list of these three people:
      John Doe (Name = John Doe, Result Count = 5, Sort Order = 2)
      Jane Doe (Name = Jane Doe, Result Count = 75, Sort Order = 3)
      Jimmy Joe (Name = Jimmy Joe, Result Count = 15, Sort Order = 1)
      Jolene Joe (Name = Jolene Joe, Result Count = 10, Sort Order = 0)


How could you define a sort on the list (using either an arraylist or generic list) that can do the following?

      Sort the list first by Sort Order (in ascending)
            Then if the Sort Order of an item is 0 or null (assume it can be a Nullable integer), sort the items that fall into this category under the others using an Alphabetical sort (in ascending order)

Or

      Sort the list first by Sort Order (in ascending)
            Then if the Sort Order of an item is 0 or null (assume it can be a Nullable integer), sort the items that fall into this category under the others using a sort of Result Count (in descending order)



Class Example

Person Class
Name (String)
ResultCount (Int)
SortOrder(Int)
endrecAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Algol36Commented:

class Person
{
   public string Name;
   public int ResultCount;
   public int SortOrder;
}

class PersonComparer : IComparer<Person>
{
   public int Compare(Person x, Person y)
   {
      if (x.SortOrder == 0 && y.SortOrder == 0)
         return x.Name.CompareTo(y.Name);
      if (x.SortOrder == 0)
         return 1;
      if (y.SortOrder == 0)
         return -1;
      return x.SortOrder.CompareTo(y.SortOrder);
   }
}  
....
List<Person> list = new List<Person>();
list.Add(new Person() { Name = "zzz", SortOrder = 0 });
list.Add(new Person() { Name = "bbb", SortOrder = 1 });
list.Add(new Person() { Name = "ccc", SortOrder = 2 });
list.Add(new Person() { Name = "xxx", SortOrder = 0 });
list.Sort(new PersonComparer());
0
endrecAuthor Commented:
How do you add a descending sort on ResultCount into the comparer, as the other sorts as acending?
0
Algol36Commented:
   
class PersonComparer : IComparer<Person>
{
   public int Compare(Person x, Person y)
   {
      if (x.SortOrder == 0 && y.SortOrder == 0)
      {
         //first compare by ResultCount
         int res = - x.ResultCount.CompareTo(y.ResultCount);
         if (res != 0)
            return res;
         //second compare by Name
         return x.Name.CompareTo(y.Name);
      }
      if (x.SortOrder == 0)
         return 1;
      if (y.SortOrder == 0)
         return -1;
      return x.SortOrder.CompareTo(y.SortOrder);
   }
}    
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
.NET Programming

From novice to tech pro — start learning today.