VB.Net/Data Structure/HashTable

Hashtable: add,get,count, Dictionary Key and value Enumerator

Imports System
Imports System.Collections
Public Class MainClass
   Public Shared Sub Main()
      Dim table As Hashtable = New Hashtable() 
   
      Dim employee As New Employee("First Name", "Last Name")
      Try
         table.Add("Last Name", employee)
         Console.WriteLine("Put: " & employee.ToString())
      Catch argumentException As ArgumentException
         Console.WriteLine(argumentException.ToString())
      End Try
      Dim result As Object = table("Last Name")
      If Not result Is Nothing Then
         Console.WriteLine("Get: " & result.ToString())
      Else
         Console.WriteLine("Get: " & "Last Name" & " not in table")
      End If

      table.Remove("Last Name")
      Console.WriteLine("table count: " & table.Count)
      Console.WriteLine("Contains key: " & table.ContainsKey("Last Name"))
      table.Clear()
      Dim enumerator As IDictionaryEnumerator = table.GetEnumerator()
      While enumerator.MoveNext()
         Console.WriteLine(Convert.ToString(enumerator.Value))
      End While

      enumerator = table.GetEnumerator()
      While enumerator.MoveNext()
         Console.WriteLine(enumerator.Key )
      End While
   End Sub
End Class

Public Class Employee
   Private firstName, lastName As String
   Public Sub New(ByVal first As String, ByVal last As String)
      firstName = first
      lastName = last
   End Sub 
   Public Overrides Function ToString() As String
      Return firstName & " " & lastName
   End Function 
End Class

Store Environment Variables into a Hash table

Imports System
Imports System.Collections
Imports System.Environment

Public Class MainClass
  Shared Sub Main()
      Dim eVariables As Hashtable
      eVariables = CType(GetEnvironmentVariables(), Hashtable)
      Dim thing As Object
      For Each thing In eVariables.Keys
            Console.WriteLine("The environment variable named " & thing.ToString() _
            & " has value " & eVariables(thing).ToString())
      Next
  End Sub
End Class