ArrayList Sorting in VB.NET - How to use ICompare

[Rob G]

Hello,

I have a basic understanding of Objects, inheritance, polymorhpism, etc. I
am new to VB.NET and I am having a problem figuring this out.

I want to sort a CheckBoxList. Using the ArrayList seemed to make the most
sense. When I use it I get the error: At least one object must implement
IComparable. Here's the code that produces that error:

Public Class Sorting
Implements IComparable, IComparer

Private Shared aryOrigData As New ArrayList
Private Shared aryChangedData As New ArrayList
Public Shared Function GatherChangedCh eckBoxData(ByVa l chkboxlist As
CheckBoxList)
Dim li As ListItem

For Each li In chkboxlist.Item s
aryChangedData. Add(li)
Next
aryChangedData. Sort()

End Function
The above code is for a web form. As I am learning to do this, I made
borrowed the code from the Help files and placed it into a new project, I
didn't get any error. Here's that code:

Imports System
Imports System.Collecti ons
Imports Microsoft.Visua lBasic
Public Class SamplesArrayLis t

Public Shared Sub Main()
' Creates and initializes a new ArrayList.
Dim myAL As New ArrayList
myAL.Add("The")
myAL.Add("quick ")
myAL.Add("brown ")
myAL.Add("fox")
myAL.Add("jumps ")
myAL.Add("over" )
myAL.Add("the")
myAL.Add("lazy" )
myAL.Add("dog")

' Displays the values of the ArrayList.
Console.WriteLi ne("The ArrayList initially contains the " _
+ "following values:")
PrintIndexAndVa lues(myAL)

' Sorts the values of the ArrayList.
myAL.Sort()

' Displays the values of the ArrayList.
Console.WriteLi ne("After sorting:")
PrintIndexAndVa lues(myAL)
End Sub 'Main
Public Shared Sub PrintIndexAndVa lues(ByVal myList As IEnumerable)
Dim i As Integer = 0
Dim myEnumerator As System.Collecti ons.IEnumerator = _
myList.GetEnume rator()
While myEnumerator.Mo veNext()
Console.WriteLi ne(ControlChars .Tab + "[{0}]:" + ControlChars.Ta b
_
+ "{1}", i, myEnumerator.Cu rrent)
i = i + 1
End While
Console.WriteLi ne()
End Sub
End Class

=============== ==============
My question is then, what is the difference between the two? Is it becuase
one is using ListItems? If that is the case how do I solve it? If it is
implementing ICompare, could someone direct me to a good source that
explains it well.

Thanks so much for your help.

[Kevin Spencer]

Try using a System.Collecti ons.SortedList instead.

--
HTH,
Kevin Spencer
..Net Developer
Microsoft MVP
Big things are made up
of lots of little things.

"Rob G" <gu*******@hotm ail.com> wrote in message
news:10******** *****@corp.supe rnews.com...

Hello,

I have a basic understanding of Objects, inheritance, polymorhpism, etc. I
am new to VB.NET and I am having a problem figuring this out.

I want to sort a CheckBoxList. Using the ArrayList seemed to make the most
sense. When I use it I get the error: At least one object must implement
IComparable. Here's the code that produces that error:

Public Class Sorting
Implements IComparable, IComparer

Private Shared aryOrigData As New ArrayList
Private Shared aryChangedData As New ArrayList
Public Shared Function GatherChangedCh eckBoxData(ByVa l chkboxlist As
CheckBoxList)
Dim li As ListItem

For Each li In chkboxlist.Item s
aryChangedData. Add(li)
Next
aryChangedData. Sort()

End Function
The above code is for a web form. As I am learning to do this, I made
borrowed the code from the Help files and placed it into a new project, I
didn't get any error. Here's that code:

Imports System
Imports System.Collecti ons
Imports Microsoft.Visua lBasic
Public Class SamplesArrayLis t

Public Shared Sub Main()
' Creates and initializes a new ArrayList.
Dim myAL As New ArrayList
myAL.Add("The")
myAL.Add("quick ")
myAL.Add("brown ")
myAL.Add("fox")
myAL.Add("jumps ")
myAL.Add("over" )
myAL.Add("the")
myAL.Add("lazy" )
myAL.Add("dog")

' Displays the values of the ArrayList.
Console.WriteLi ne("The ArrayList initially contains the " _
+ "following values:")
PrintIndexAndVa lues(myAL)

' Sorts the values of the ArrayList.
myAL.Sort()

' Displays the values of the ArrayList.
Console.WriteLi ne("After sorting:")
PrintIndexAndVa lues(myAL)
End Sub 'Main
Public Shared Sub PrintIndexAndVa lues(ByVal myList As IEnumerable)
Dim i As Integer = 0
Dim myEnumerator As System.Collecti ons.IEnumerator = _
myList.GetEnume rator()
While myEnumerator.Mo veNext()
Console.WriteLi ne(ControlChars .Tab + "[{0}]:" + ControlChars.Ta b _
+ "{1}", i, myEnumerator.Cu rrent)
i = i + 1
End While
Console.WriteLi ne()
End Sub
End Class

=============== ==============
My question is then, what is the difference between the two? Is it becuase
one is using ListItems? If that is the case how do I solve it? If it is
implementing ICompare, could someone direct me to a good source that
explains it well.

Thanks so much for your help.

[Rob G]

Thanks for the tip. I'll look into it.

"Kevin Spencer" <ks******@takem pis.com> wrote in message
news:OY******** *****@TK2MSFTNG P10.phx.gbl...

Try using a System.Collecti ons.SortedList instead.

--
HTH,
Kevin Spencer
.Net Developer
Microsoft MVP
Big things are made up
of lots of little things.

"Rob G" <gu*******@hotm ail.com> wrote in message
news:10******** *****@corp.supe rnews.com...

Hello,

I have a basic understanding of Objects, inheritance, polymorhpism, etc. I am new to VB.NET and I am having a problem figuring this out.

I want to sort a CheckBoxList. Using the ArrayList seemed to make the most sense. When I use it I get the error: At least one object must implement
IComparable. Here's the code that produces that error:

Public Class Sorting
Implements IComparable, IComparer

Private Shared aryOrigData As New ArrayList
Private Shared aryChangedData As New ArrayList
Public Shared Function GatherChangedCh eckBoxData(ByVa l chkboxlist As
CheckBoxList)
Dim li As ListItem

For Each li In chkboxlist.Item s
aryChangedData. Add(li)
Next
aryChangedData. Sort()

End Function
The above code is for a web form. As I am learning to do this, I made
borrowed the code from the Help files and placed it into a new project, I didn't get any error. Here's that code:

Imports System
Imports System.Collecti ons
Imports Microsoft.Visua lBasic
Public Class SamplesArrayLis t

Public Shared Sub Main()
' Creates and initializes a new ArrayList.
Dim myAL As New ArrayList
myAL.Add("The")
myAL.Add("quick ")
myAL.Add("brown ")
myAL.Add("fox")
myAL.Add("jumps ")
myAL.Add("over" )
myAL.Add("the")
myAL.Add("lazy" )
myAL.Add("dog")

' Displays the values of the ArrayList.
Console.WriteLi ne("The ArrayList initially contains the " _
+ "following values:")
PrintIndexAndVa lues(myAL)

' Sorts the values of the ArrayList.
myAL.Sort()

' Displays the values of the ArrayList.
Console.WriteLi ne("After sorting:")
PrintIndexAndVa lues(myAL)
End Sub 'Main
Public Shared Sub PrintIndexAndVa lues(ByVal myList As IEnumerable)
Dim i As Integer = 0
Dim myEnumerator As System.Collecti ons.IEnumerator = _
myList.GetEnume rator()
While myEnumerator.Mo veNext()
Console.WriteLi ne(ControlChars .Tab + "[{0}]:" +

ControlChars.Ta b

_
+ "{1}", i, myEnumerator.Cu rrent)
i = i + 1
End While
Console.WriteLi ne()
End Sub
End Class

=============== ==============
My question is then, what is the difference between the two? Is it becuase one is using ListItems? If that is the case how do I solve it? If it is
implementing ICompare, could someone direct me to a good source that
explains it well.

Thanks so much for your help.