from list to string with formatting - vb.net

Question

i have a function getSelectedNumbers that take as input 3 list of number. after a manipulation i need to obtain a string in the format
"[1_3,10,20,30,500],[1_1,2],[]"
if the list is empty i need to have in the string the "[]" char
i wrote the below function but i need to manage the empty case.
Based on comment of Anu6is :
i was able to rewrite my code as below
'''vb
Public Function getSelectedNumbers() As String
Dim selectedNumbers1 As IList(Of Element) = repo.CanvasTerminalProduct.BoardDetails.Panel.pnlSuper3Panel1.Find(".//div[#class='selected']")
Dim selectedNumbers2 As IList(Of Element) = repo.CanvasTerminalProduct.BoardDetails.Panel.pnlSuper3Panel2.Find(".//div[#class='selected']")
Dim selectedNumbers3 As IList(Of Element) = repo.CanvasTerminalProduct.BoardDetails.Panel.pnlSuper3Panel3.Find(".//div[#class='selected']")
Dim list1 As New List(Of String)
Dim list2 As New List(Of String)
Dim list3 As New List(Of String)
For i As Integer = 0 To selectedNumbers1.Count -1
list1.Add(selectedNumbers1(i).GetAttributeValue("innerText").ToString)
Next i
For i As Integer = 0 To selectedNumbers2.Count -1
list2.Add(selectedNumbers2(i).GetAttributeValue("innerText").ToString)
Next i
For i As Integer = 0 To selectedNumbers3.Count -1
list3.Add(selectedNumbers3(i).GetAttributeValue("innerText").ToString)
Next i
'Create List of List
Dim selectedNumbersList As New List(Of List(Of String)) From {list1, list2, list3}
Dim builder As New StringBuilder 'Used to build the output
'Convert all the list in the correct string format using the join
For Each listX As List(Of String) In selectedNumbersList
builder.Append("[1_").Append(String.Join(",", listX)).Append("],") 'String.Join() give you a comma delmited string
Next
'Remove the last, and the [1_] that are not needed
Dim strSelectedNunmber As String = builder.ToString().TrimEnd(","c)
strSelectedNunmber = strSelectedNunmber.ToString().Replace("[1_]","[]")
Return str
End Function
'''
now my question is there is a better way to generate the list1 list2 list3 ?

Answer 1

This is assuming that Element is simply an Integer
Public Function getSelectedNumbers() As String
Dim selectedNumbers1 As New List(Of Integer) From {20, 30, 500, 10, 3} 'Unordered list
Dim selectedNumbers2 As New List(Of Integer) From {1, 2, 500} 'Ordered list
Dim selectedNumbers3 As New List(Of Integer) 'empty list
Dim selectedNumbersList As New List(Of List(Of Integer)) From {selectedNumbers1, selectedNumbers2, selectedNumbers3}
Dim builder As New StringBuilder 'Used to build the output
For Each list In selectedNumbersList
list.Sort() 'Sort your list
builder.Append("[").Append(String.Join(",", list)).Append("],") 'String.Join() give you a comma delmited string
Next
Return builder.ToString.TrimEnd(","c) 'Remove the final comma (,) and return the formatted string
End Function
[3,10,20,30,500],[1,2,500],[]

Answer 2

Does this work for you?
Dim selectedNumbers1 As New List(Of Integer) From {20, 30, 500, 10, 3}
Dim selectedNumbers2 As New List(Of Integer) From {1, 2, 500}
Dim selectedNumbers3 As New List(Of Integer)
'either make 3 loops or 1, but you have to make a list of lists first
Dim selectedNumbersList As New List(Of List(Of Integer)) From {selectedNumbers1, selectedNumbers2, selectedNumbers3}
For Each listX In selectedNumbersList
listX.Sort()
Dim ReturnString As String = "["
If listX.Count > 0 Then
For Each itemvalue In listX
ReturnString &= itemvalue & ","
Next
ReturnString = ReturnString.Remove(ReturnString.Length - 1)
End If
ReturnString &= "]"
Debug.Print(ReturnString)
Next
'[3,10,20,30,500]
'[1,2,500]
'[]