How sort a System.Collections.Generic.List in VB.Net?

Question

I using a genric list(m_equipmentList ) which is collection of objects (Schedule_Payitem).
How can sort list according to a proerty of child object ?

Dim m_         


        

Answer 1

Are you using VB9? If so, I'd use a lambda expression to create a Comparer(Of Schedule_PayItem). Otherwise, write a short class to implement IComparer(Of Schedule_PayItem). pass whichever one you've got into List.Sort.

An example for the lambda expression (untested):

m_equipmentList.Sort(Function(p1, p2) p1.ResourceID.CompareTo(p2.ResourceID))

And for the IComparer(Of Schedule_PayItem):

Public Class PayItemResourceComparer
    Implements IComparer(Of Schedule_PayItem)
    Public Function Compare(ByVal p1 As Schedule_PayItem, _
                            ByVal p2 As Schedule_PayItem) As Integer
        Return p1.ResourceID.CompareTo(p2.ResourceID)
    End Function
End Class

...

m_equipmentList.Sort(New PayItemResourceComparer)

Answer 2

Try this

Dim m_equipmentList As New List(Of Schedule_Payitem)


m_equipmentList.Sort(delegate(Schedule_Payitem p1, Schedule_Payitem p2)
              {
                  return p1.resourceid .CompareTo(p2.resourceid );
              });

Answer 3

I don't know vb.net so I did it in C#

m_equipmentList.Sort(
   (payItem1,payItem2)=>payItem1.ResourceID.CompareTo(payItem2.ResourceID));

and using the reflector translated it to vb.net hope it helps

m_equipmentList.Sort(
Function (ByVal payItem1 As Schedule_Payitem, ByVal payItem2 As Schedule_Payitem) 
    Return payItem1.ResourceID.CompareTo(payItem2.ResourceID)
End Function)

or you can inherit Schedule_Payitem from IComparable and implement CompareTo and then just call m_equipmentList.Sort()

Answer 4

You can accomplish sorting the list in descending order by changing this-

m_equipmentList.Sort(
Function (ByVal payItem1 As Schedule_Payitem, ByVal payItem2 As Schedule_Payitem) 
    Return payItem1.ResourceID.CompareTo(payItem2.ResourceID)
End Function)

to this

m_equipmentList.Sort(
Function (ByVal payItem1 As Schedule_Payitem, ByVal payItem2 As Schedule_Payitem) 
    Return payItem2.ResourceID.CompareTo(payItem1.ResourceID)
End Function)