I can't find the error here....

16 Mar 2006 7:09 AM

Radu

Hi. I have the following:

___________________________________________________________________________________
Public Class SquareDictionary
Inherits System.Collections.DictionaryBase

Default Property Item(ByVal key As String) As Square
Get
       Return CType(Dictionary.Item(key), Square)
End Get
Set(ByVal Value As Square)
       Dictionary.Item(key) = Value
End Set
End Property

Sub Add(ByVal key As String, ByVal value As Square)
      Dictionary.Add(key, value)
End Sub

'Sa ample "Factory function"
Function Create(ByVal key As String, ByVal side As Single) As Square
      Create = New Square(side)
      dictionary.Add(key, Create)
End Function

Class Square
      Implements IComparable

      Public Side As Integer

      Sub New(ByVal side As Integer)
          Me.Side = side
      End Sub

      Public Function CompareTo(ByVal obj As Object) As Integer Implements
System.IComparable.CompareTo
          If obj Is Nothing Then Return 1
          Dim other As Square = CType(obj, Square)
          If Side > other.Side then return 1
          If Side = other.Side then return 0
          If Side < other.Side then return -1
      End Function
    End Class
End Class
___________________________________________________________________________________
Module Module1

Sub Main()

Dim sq As New SquareDictionary()

'Add normally
sq.Add("First", New SquareDictionary.Square(10))
sq.Add("Second", New SquareDictionary.Square(20))
sq.Add("Third", New SquareDictionary.Square(30))

'Add using the "factory function"
sq.Create("Fourth", 40)
sq.Create("Fifth", 50)
sq.Create("Sixth", 60)

Dim s As DictionaryEntry
For Each s In sq
    Console.Write(s.Key + ", ")
    Dim ss As SquareDictionary.Square = CType(s.Value,
SquareDictionary.Square)
    Console.WriteLine(ss.Side)
Next

Dim a(sq.Count) As DictionaryEntry
sq.CopyTo(a, 1)
'Array.Sort(a)

Dim i As Integer
For i = 1 To a.GetUpperBound(0)
    Console.WriteLine(CType(a(i).Value, SquareDictionary.Square).Side)
Next
Console.Read()
End Sub
End Module
___________________________________________________________________________________

The code works just fine, producing:

Sixth, 60
Fifth, 50
Third, 30
Second, 20
First, 10
Fourth, 40
60
50
30
20
10
40

But now I want to add the sort capability, so I added the Function CompareTo
in SquareDictionary.Square.
I get the error "Additional information: Specified IComparer threw an
exception."

Where is my error ? In my mind, it should work.... what am I missing here ?
Thanks a lot.
Alex

16 Mar 2006 10:01 AM

R. MacDonald

Hello, Alex,

I suspect the problem might be with:

> Dim other As Square = CType(obj, Square)

Perhaps obj is not the Type that you think. For example, I see in your
output line:

> Console.WriteLine(CType(a(i).Value, SquareDictionary.Square).Side)

that you are casting a(i).Value to Square. Maybe you also need to cast
obj.Value to Square in the CompareTo function.

You should be able to test this by setting a breakpoint on the line
doing the casting in CompareTo and test the type that is being cast.

Cheers,
Randy

Radu wrote:

Show quoteHide quote

> Hi. I have the following:
>
> ___________________________________________________________________________________
> Public Class SquareDictionary
> Inherits System.Collections.DictionaryBase
>
> Default Property Item(ByVal key As String) As Square
>   Get
>        Return CType(Dictionary.Item(key), Square)
>   End Get
>   Set(ByVal Value As Square)
>        Dictionary.Item(key) = Value
>   End Set
> End Property
>
> Sub Add(ByVal key As String, ByVal value As Square)
>       Dictionary.Add(key, value)
> End Sub
>
> 'Sa ample "Factory function"
> Function Create(ByVal key As String, ByVal side As Single) As Square
>       Create = New Square(side)
>       dictionary.Add(key, Create)
> End Function
>
> Class Square
>       Implements IComparable
>
>       Public Side As Integer
>
>       Sub New(ByVal side As Integer)
>           Me.Side = side
>       End Sub
>
>       Public Function CompareTo(ByVal obj As Object) As Integer Implements
> System.IComparable.CompareTo
>           If obj Is Nothing Then Return 1
>           Dim other As Square = CType(obj, Square)
>           If Side > other.Side then return 1
>           If Side = other.Side then return 0
>           If Side < other.Side then return -1
>       End Function
>     End Class
> End Class
> ___________________________________________________________________________________
> Module Module1
>
> Sub Main()
>
>   Dim sq As New SquareDictionary()
>
>   'Add normally
>   sq.Add("First", New SquareDictionary.Square(10))
>   sq.Add("Second", New SquareDictionary.Square(20))
>   sq.Add("Third", New SquareDictionary.Square(30))
>
>   'Add using the "factory function"
>   sq.Create("Fourth", 40)
>   sq.Create("Fifth", 50)
>   sq.Create("Sixth", 60)
>
>   Dim s As DictionaryEntry
>   For Each s In sq
>     Console.Write(s.Key + ", ")
>     Dim ss As SquareDictionary.Square = CType(s.Value,
> SquareDictionary.Square)
>     Console.WriteLine(ss.Side)
>   Next
>
>   Dim a(sq.Count) As DictionaryEntry
>   sq.CopyTo(a, 1)
>   'Array.Sort(a)
>
>   Dim i As Integer
>   For i = 1 To a.GetUpperBound(0)
>     Console.WriteLine(CType(a(i).Value, SquareDictionary.Square).Side)
>   Next
>   Console.Read()
> End Sub
> End Module
> ___________________________________________________________________________________
>
> The code works just fine, producing:
>
> Sixth, 60
> Fifth, 50
> Third, 30
> Second, 20
> First, 10
> Fourth, 40
> 60
> 50
> 30
> 20
> 10
> 40
>
> But now I want to add the sort capability, so I added the Function CompareTo
> in SquareDictionary.Square.
> I get the error "Additional information: Specified IComparer threw an
> exception."
>
> Where is my error ? In my mind, it should work.... what am I missing here ?
> Thanks a lot.
> Alex
>
>

16 Mar 2006 10:24 AM

José_Manuel_Agüero

Hello Radu,

Change your line to:
Array.Sort(a, New SquareDictionaryComparer)

And add the following class:

Class SquareDictionaryComparer

    Implements IComparer

    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare

        Dim one As SquareDictionary.Square = CType(CType(x, DictionaryEntry).Value, SquareDictionary.Square)

        Dim other As SquareDictionary.Square = CType(CType(y, DictionaryEntry).Value, SquareDictionary.Square)

        If one Is Nothing Then

            If other Is Nothing Then

                Return 0

            Else

                Return -1

            End If

        Else

            Return one.CompareTo(other)

        End If

    End Function

End Class

Regards.

Show quoteHide quote

21 Mar 2006 1:04 AM

Radu

Thank you. I learned from your answers.

Thanks again,
Alex.