Android Question How to sort a string?

Dim strVar As String="4132"
Dim strNewVar As String
Dim MyList As List
MyList.Initialize
For i=0 To strVar.Length-1
  MyList.Add(strVar.SubString2(i,i+1))
Next
MyList.Sort(True)
For i=0 To MyList.Size-1
  strNewVar= strNewVar & MyList.Get(i)
Next
Msgbox(strNewVar,"") 'returns 1234

    Dim str As String = "4132"
    Dim Swapped As Boolean
    Swapped = True
    Do While Swapped
        Swapped = False
        For i = 1 To str.Length-1
            If Asc(str.CharAt(i)) < Asc(str.CharAt(i-1)) Then
                str=str.SubString2(0,i-1)&str.SubString2(i,i+1)&str.SubString2(i-1,i)&str.SubString(i+1)
                Swapped = True
            End If
        Next
    Loop

    Log(str)

    Dim str As String = "1432"  
    Dim num As Int
    Dim PigeonHole(5) As Boolean
    For i = 0 To str.Length-1
        num = str.SubString2(i,i+1)
        PigeonHole(num)=True
    Next
    str=""
    For i = 1 To 4
        If PigeonHole(i) = True Then str=str&i
    Next
  
    Log(str)