Sort and Search arrays using IComparable

[alreadyused]

I am looking for feedback on this code/idea.

 

What I want to do is load tables and throw away tables as needed. Some tables I will want to keep loaded for a while.

 

For example, at runtime I find that i need a table so I try to get it from an array.

If it's there, get it, if not load it (this isn't shown below; I add 5 dummy tables for testing)

When I'm done with it (whenever that may be) I remove it.

 

I started with the code basically mimicking PlausiblyDamp's suggestion in this post:

http://www.xtremedotnettalk.com/showthread.php?t=83236

It sorted fine, but when I went to do a search on the array, it crashed because I was passing the table name and not a "TableClass", and it was trying to cast a string to type TableClass.

 

Again starting from one of PD's suggestions from here:

http://www.xtremedotnettalk.com/showthread.php?t=82561

I tested the object passed in to make sure it has a toString function.

Sooooo, here is a very basic test for what I'm wanting to do:

 

Module modMain
 Sub Main()

   Dim oTest As New FindTest
   Dim name As String
   For i As Integer = 1 To 5
     name = "a" & i.ToString
     oTest.addTable(name)
   Next

   Dim tbl As TableClass = oTest.findTable("a1")
   MessageBox.Show(tbl.getName)

   oTest.removeTable("a3")

 End Sub
End Module


Public Class FindTest
 Private tbl() As TableClass

 Public Sub addTable(ByVal name As String)
   
   Dim xd As New Xml.XmlDocument
   Dim o As New TableClass(name, xd)
   Dim i As Integer

   If Me.tbl Is Nothing Then
     i = 0
   Else
     i = Me.tbl.GetUpperBound(0) + 1
   End If

   ReDim Preserve Me.tbl(i)
   Me.tbl(i) = o
   Me.tbl.Sort(Me.tbl)
 End Sub

 Public Function findTable(ByVal name As String) As TableClass
   Dim i As Integer = Me.tbl.BinarySearch(Me.tbl, name)
   Return tbl(i)
 End Function

 Public Function removeTable(ByVal name As String) As TableClass
   Dim t1() As TableClass
   Dim count As Integer = -1

   Dim i As Integer = Me.tbl.BinarySearch(Me.tbl, name)

   If i >= 0 Then
     For j As Integer = 0 To Me.tbl.Length - 1
       If j <> i Then
         count += 1
         ReDim Preserve t1(count)
         t1(count) = Me.tbl(j)
       End If
     Next
   End If

   Me.tbl = t1

 End Function
End Class


Public Class TableClass
 Implements IComparable

 Private name As String
 Private table As Xml.XmlDocument

 Public Sub New(ByVal name As String, ByVal table As Xml.XmlDocument)
   Me.name = name
   Me.table = table
 End Sub
 Public Function getName() As String
   Return Me.name
 End Function
 Public Function getTable() As Xml.XmlDocument
   Return Me.table
 End Function
 Public Overrides Function toString() As String
   Return Me.name
 End Function

 Public Function CompareTo(ByVal obj As Object) As Integer Implements System.IComparable.CompareTo
   Try
     Dim name As String = obj.ToString
   Catch ex As Exception
     Throw New InvalidOperationException("Objects must have toString function for comparison.")
   End Try

   If String.Compare(Me.name, name) < 0 Then Return -1
   If String.Compare(Me.name, name) > 0 Then Return 1
   Return 0

 End Function
End Class

 

This code compiles and runs fine; does what I want it to do.

 

What I'm curious about is:

1. Does this make sense to be doing this?
   
2. Is there an easier or more efficient way to remove an item from an array?
   
3. Am I doing the Compare correctly?
   
4. Does anyone see any other errors or things I should improve on?
   

 

Thanks in advance!

[MrPaul]

Consider a Dictionary

 

Personally I would suggest using a Dictionary or Hashtable to associate each TableClass with its name. Unless you have a need to sort the tables besides faster access (which the Dictionary provides) this would definitely be preferable. It would also take care of resizing the collection as tables are inserted or removed, and more efficiently than your code appears to do.

 

On an unrelated note, all objects expose a ToString method so the try/catch block would be unnecessary.

 

Good luck :)

[alreadyused]

Re: Consider a Dictionary

 

awesome on the try/catch! figures, i looked over this and was thinking, ok, i'm not doing anything stupid... ooops

 

I don't need the tables sorted other than for fetching or removing.

 

I'll check out the dictionary, thanks!

[alreadyused]

Re: Consider a Dictionary

 

wow.... so.....

 

EASY!!!!!!!!!

 

Thanks for the tip!