RANDOM Sorting Objects in ArrayList

[jesus4u]

Please help me figure out how to sort this array list in a random sort.

Thanks

        Private Sub BindBanners()
            Dim ar As New ArrayList
            Dim path As String = "images/banners/"

            Dim item As New Telerik.WebControls.RotatorDataItem
            item("BannerLocation") = path & "home.jpg"
            ar.Add(item)

            Dim item1 As New Telerik.WebControls.RotatorDataItem
            item1("BannerLocation") = path & "about.jpg"
            ar.Add(item1)

            Dim item2 As New Telerik.WebControls.RotatorDataItem
            item2("BannerLocation") = path & "contact.jpg"
            ar.Add(item2)

            Dim item3 As New Telerik.WebControls.RotatorDataItem
            item3("BannerLocation") = path & "links.jpg"
            ar.Add(item3)

            Dim item4 As New Telerik.WebControls.RotatorDataItem
            item4("BannerLocation") = path & "news.jpg"
            ar.Add(item4)

            Dim item5 As New Telerik.WebControls.RotatorDataItem
            item5("BannerLocation") = path & "service.jpg"
            ar.Add(item5)

            Dim item6 As New Telerik.WebControls.RotatorDataItem
            item6("BannerLocation") = path & "gallery.jpg"
            ar.Add(item6)

            Dim item7 As New Telerik.WebControls.RotatorDataItem
            item7("BannerLocation") = path & "gallery2.jpg"
            ar.Add(item7)

            'Generate random value
            Randomize()
            Dim MyValue As Integer = CInt(Int((ar.Count * Rnd()) + 1))
            ar.Sort(MyValue, ar.Count - 1, Nothing)

            RadRotator1.DataSource = ar
            RadRotator1.DataBind()
        End Sub 'BindBanners

[Flac]

im kind of new to VB so this is probably the worst possible way to accomplish what you want... But you could always do either a case statement, or an If-then-elseif statement for each random number and change the location of the variables in the array...

Its tedious, and i may actauly have no idea what your trying to accomplish, but it would work...i think :/

--Flac

[pax]

Hi.

I guess you could make your own sorting class that implements IComparer.

In that you would create a function with 2 args. representing the 2 objects to be compared.

then just return a random number of -1,0,1.

-1 means X<Y
0 means X=Y
1 menas X>Y

When you sort you could pass a new instance of your comparerclass as an argument.

I haven't tried it on ArrayList before, but I have used the method of sorting all kinds of other objects, including my own classes.

Edit:
I have just done a few test's and it seems that returning random numbers in a comparerclass might not be as easy as I first expected Apperantly i relies on a "0" being returned at a certain time. I've never seen this behaviour when sorting normally, but If I return random numbers it throws an exception sometimes.
So it seems my "solution" might not be the right one, but at least I'm sure you can use the info about the comparerclass to something anyway.

Sorry I couldn't be of any more help.

[Mike Hildner]

Depending how how random you want, you can go the easy way or look up some good algorithm.

The easy way is to loop through all your elements, swapping randomly . i.e., if you have 8 total elements:

Swap #1 with 1,2,3,4,5,6,7 or 8
Swap #2 with 1,2,3,4,5,6,7 or 8
Swap #3 with 1,2,3,4,5,6,7 or 8

etc.

I'm no mathmatician, but if I understand what I've read, this becomes less random with a larger number of elements. I'm not smart enough to explain that, but it probably doesn't make a difference for "randomizing" banners.

Mike