Visual Studio.NET Programming Problem

• Xcert

  2 Jul 05, 21:10

  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?
• Ito_^

  2 Jul 05, 21:21

  Originally posted by Xcert:

  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?

  try.. List.SelectedItem.Value instead, can't be sure, returned everything to lecturer.
• Xcert

  2 Jul 05, 21:30

  Originally posted by Ito_^:

  try.. List.SelectedItem.Value instead, can't be sure, returned everything to lecturer.

  Nope...its not valid.Thanks anyway...
  
  Any other suggestions around?
• hjxfabio

  2 Jul 05, 21:38

  Originally posted by Xcert:

  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?

  Does the Listbox has a data source? Or just filled with string values?
• Xcert

  2 Jul 05, 21:41

  Originally posted by hjxfabio:

  Does the Listbox has a data source? Or just filled with string values?

  err...I am not too sure what U mean by data source...the listbox is filled with filenames from a OpenFileDialog.
• octega

  2 Jul 05, 21:46

  If it is a VB6 problem, the problem is most likely, have to
  reDIM the arrary to the number of items in the listbox/etc.
  
  something like this:- reDIM Array((TotalItemsinList - 1))
  
  But not sure if thats the case for VB.NET
• Xcert

  2 Jul 05, 21:51

  Originally posted by octega:

  If it is a VB6 problem, the problem is most likely, have to
  reDIM the arrary to the number of items in the listbox/etc.
  
  But not sure if thats the case for VB.NET

  tried the redim...doesnt work...I think the problem is with incompatible data types in the statement but I cannot find the error...also tried dim array as object...also cannot work.
• one-niner

  3 Jul 05, 00:38

  Originally posted by Xcert:
  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?[/b]

  i didn't use VB.NET, but from your code in bold, your declaring an variable called "Array" of String type. Therefore your variable "Array" is a immutable array of characters aka String datatype. so if u declare your variable Array as a string ur are impling that this string variable can only store ONE string value.
  
  Dim Array() as String;
  Array="wilson";
  therefore element [0] = "w";
  and element [2] = "l" ;
  
  get it so far ?
  
  what u intend or i understand u want to do ..is an Array of Strings ...in java, its easy as u just declare an ArrayList and u just dump all the string values into the ArrayList.And i know Arraylist exist for C#, so i do belive that the data type is supported in VB.NET, unless your using the compact framework.
  
  this is my syntax, sorry if i make some syntax errors as i didn't code in VB.NET and i did much of my coding in C# and Java.
  
  Dim counter as Integer;
  Dim myListBoxValue as ArrayList;
  
  For Counter = 0 To TotalItemsinList - 1
  myListBoxValue(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
• pie

  3 Jul 05, 01:07

  Originally posted by Xcert:
  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?

  Are those items in bold still valid? Might have removed them or nulled them somewhere in yr program?
  
  List.SelectedItem seems to be a property, so it might not return you the actual value
  
  Might also want to try to initialise Array()...think it was Dim Array() As New String
• afei

  3 Jul 05, 01:51

  i dun think u need to do a system .convertto in this case u can straight away put
  
  array(counter) = List1.SelectedItem
  
  but somehow u logic of ur code is a bit strange to me if u are putting every item in the listbox to the array then there is logic error in your code
• k4korny

  3 Jul 05, 02:38

  Originally posted by Xcert:
  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  

  Where did it say the error was?
  think there may be 3 possible problem:
  1) Array is a name of a class in .Net framework. so if the error is at "Dim Array() As String".. then change the name of your array to something like " Dim aryListStrings() as String"
  
  2) The size of the array was not declared. Try "Dim aryListStrings(10) as String"
  
  3) Instead of "List.SelectedItem", use "List.SelectedItem.ToString" or "List.Text"
  
  IMO.. most likely, the problem is (2)... cos the memory for the array was not allocated yet, since you haven't declared its size.
  
• pisces8

  3 Jul 05, 08:10

  
• hjxfabio

  4 Jul 05, 10:26

  Originally posted by Xcert:

  Dim Counter As Integer
  Dim Array() As String
  
  For Counter = 0 To TotalItemsinList - 1
  Array(Counter) = System.Convert.ToString(List.SelectedItem)
  Next Counter
  
  Basically I just want to put the items I have selected in the Listbox into the array.
  
  For the above code...I get the error message "Object reference not set to an instance of an object."...Any experts here know what's the problem?

  Dim Counter As Integer
  Dim Array(List.SelectedItems.Count - 1) As String
  
  For Counter = 0 To List.SelectedItems.Count - 1
  Array(Counter)=System.Convert.ToString(List.SelectedItems(Counter))
  Next Counter
  
  Try to see if this code works.
• Xcert

  13 Jul 05, 21:06

  Originally posted by hjxfabio:
  
  
  Dim Counter As Integer
  Dim Array([b]List.SelectedItems.Count - 1) As String
  
  For Counter = 0 To List.SelectedItems.Count - 1
  Array(Counter)=System.Convert.ToString(List.SelectedItems(Counter))
  Next Counter
  
  Try to see if this code works.[/b]

  yup.It works.
  Thanks.
• hjxfabio

  16 Jul 05, 01:48

  Originally posted by Xcert:

  yup.It works.
  Thanks.

  Welcome..