[RESOLVED] [2005] in need of a good idea

[Bongo]

Greetings,

i have a structure element in my code which looks like

    Public Structure EventItem
        Dim Start As Date
        Dim Finish As Date
        Dim Duration As Date
        Dim Subject As String
        Dim Tag As String
        Dim EventColor As Color
        Dim EventNo As Integer
        Dim TotalEventsOnDay As Integer
    End Structure

which will be stored in a list

    Public EventList As New List(Of EventItem)

in runtime the structure will be filled like this

        Dim ItemE As New MonthCalendar.MonthView.EventItem

        ItemE.Subject = "Test1"
        ItemE.Tag = "Test1"
        ItemE.Start = CDate("27.03.2007 02:15")
        ItemE.Finish = DateAdd(DateInterval.Hour, 1, ItemE.Start)
        ItemE.Duration = CDate("27.03.2007 02:15")
        ItemE.EventColor = Color.Red
        ItemE.EventNo = ??????????????        
        ItemE.TotalEventsOnDay = ??????????
        cstMonthView.EventList.Add(ItemE)

my problem now ist

1. How do i know how many events with the same day are allready in the list

[kleinma]

you would have to write a method that would enumerate the list, and count that information.

If you would need to do this often, I would suggest writing a class that inherits from list, so that you can encapsulate that method in the class itself, and call it whenever needed from your code.

[Bongo]

you would have to write a method that would enumerate the list, and count that information.

If you would need to do this often, I would suggest writing a class that inherits from list, so that you can encapsulate that method in the class itself, and call it whenever needed from your code.

Thanks kleinma

do you know any code sample where i can see how i archive this?

[jmcilhinney]

First of all I would suggest using a class rather than a structure. I would also suggest making all those fields private and exposing them through public properties. Properties are preferable to fields for various reasons, not least of which is the fact that you cannot use fields in data binding.

Whether you choose to accept that advice or not, your collection could look something like this:

Public Class EventItemCollection
    Inherits System.Collections.ObjectModel.Collection(Of EventItem)
 
    ''' <summary>
    ''' Gets a count of the number of EventItems in the collection with the specified Start value.
    ''' </summary>
    ''' <param name="start">
    ''' The start date to match.
    ''' </param>
    Public Function GetCountWithStart(ByVal start As Date) As Integer
        Dim count As Integer = 0
 
        For Each item As EventItem In Me.Items
            If item.Start = start Then
                count += 1
            End If
        Next item
 
        Return count
    End Function
 
End Class

The Collection(Of T) class provides all the standard collection behaviour for you so you only have to provide any custom behaviour.

[Bongo]

@jmcilhinney

I tried to follow your suggestion and I messed it up majorly. Would you please have a look on the attached test.zip.

thanks in advance

Manfred

[jmcilhinney]

There's not much to mess up. You've already got the code for the collection. If you want to take my advice with regards to the EventItem type then it would look like this:

Public Class EventItem
 
    Private _start As Date
 
    Public Property Start() As Date
        Get
            Return _start
        End Get
        Set(ByVal value As Date)
            _start = value
        End Set
    End Property
 
End Class

That's for changing the Structure to a Class and the Start field to a property. All the other fields would be handled similarly.

[Bongo]

I did this and I created a class DayItem, EventItem and EventItemCollection. And Impotet them into the Monthview class, but it looks like now the list is not holding the different items only the last

[jmcilhinney]

I haven't looked at your attachment and I'm not going to. Just note that structures are value types and classes are reference types. If you create a structure instance and add it to a collection 10 times, changing the property values each time then you'll end up with 10 different structure instances in the collection. That's because each time you are adding a copy of the structure to the collection. If you do the same thing with a class you'll get a totally different result. The collection will contain 10 references all to the same class instance and it will only contain the last property values you set. If you want 10 class instances then you have to create 10 distinct instances, i.e. use the New keyword 10 times.

[Bongo]

OK now I understand my mistake - i declared on top of the methode
Dim ItemSquare as new DayItem - but I needed it to do in the loop where the 42 different ItemSquares are been filled and putet into the list.
Ok one major Problem solved many thanks - Manfred