Sorting contents of a listbox - arrays

Question

I'm using the following code to add items to a listbox:
Dim i As Integer = 0
Dim temp As String
ListBox2.Items.Clear()
While i <= 9
temp = Str(final_average(i)) + " " + Str(i + 1) + " " + Str(cals(i))
ListBox2.Items.Add(temp)
i = i + 1
End While
I want to sort this using the average or final_average(i), but the following code doesn't seem to work:
Dim arr(ListBox2.Items.Count - 1) As Object
ListBox2.Items.CopyTo(arr, 0)
Array.Sort(arr)
ListBox2.Items.Clear()
ListBox2.Items.AddRange(arr)
How do I sort the contents of the listbox?
(Note: This is not homework but part of a bigger project).

Answer 1

Here is the proper way to do it.
A. First create your list items class.
Public Class MyListItem
Implements IComparable(Of MyListItem)
Public FinalAverage As Integer
Public Number As Integer
Public Cals As Integer
Public Sub New(ByVal finalAverage As Integer, ByVal number As Integer, ByVal cals As Integer)
Me.FinalAverage = finalAverage
Me.Number = number
Me.Cals = cals
End Sub
Public Overrides Function ToString() As String
'' the way you want it to be shown in the listbox.
Return String.Format("{0} {1} {2}", FinalAverage, Number, Cals)
End Function
Public Function CompareTo(ByVal other As MyListItem) As Integer Implements System.IComparable(Of MyListItem).CompareTo
'' the way list items are compared for sorting... Return 0 for equal, -1 for smaller, +1 for bigger
If Me.FinalAverage < other.FinalAverage Then Return -1
If Me.FinalAverage > other.FinalAverage Then Return 1
Return 0
End Function
End Class
B. Now use this class to add items to your listbox.
Dim listItems As New List(Of MyListItem)
For i As Integer = 0 To 9
listItems.Add(New MyListItem(final_average(i), i + 1, cals(i)))
Next
listItems.Sort()
ListBox2.DataSource = listItems
And that's it! :)

Answer 2

I have a rather simpler solution to your problem!
Method 1
1) Sort the items in Listbox1:
We will do this by setting the Sorted property of Listbox1 to True. It will keep your old list which was not sorted safely!
listBox1.Sorted = True
2) Send the items to Listbox2:
Copy all the items from listbox1 to listbox2 by saving it to an object collection. They will move in order, and hence, the second one is sorted from A-Z.
Dim objCollection As Object() = New Object(listBox1.Items.Count - 1)
listBox1.Items.CopyTo(objCollection, 0)
listBox2.Items.AddRange(objCollection)
3) Place items in Listbox1 in proper order:
We have both the listbox with sorted items. Now, all we need to do is to place items in the previous order. As I said, your placement of items will be stored safely, we will retrieve it back by setting the Sorted property of Listbox1 to False.
listBox1.Sorted = False
And, you will get a sorted listbox2!
Method 2
Instead of sorting and then copying and then unsorting listbox1, you can first copy all items to listbox2 and then sort listbox2. In this case, there will be no need of unsorting the first one again!
I hope it works perfectly!