Imports System
Imports System.Collections
Imports System.Collections.Specialized
Public Class MyCollection
Inherits NameObjectCollectionBase
Private _de As New DictionaryEntry()
' Gets a key-and-value pair (DictionaryEntry) using an index.
Default Public ReadOnly Property Item(index As Integer) As DictionaryEntry
Get
_de.Key = Me.BaseGetKey(index)
_de.Value = Me.BaseGet(index)
Return _de
End Get
End Property
' Adds elements from an IDictionary into the new collection.
Public Sub New(d As IDictionary)
Dim de As DictionaryEntry
For Each de In d
Me.BaseAdd(CType(de.Key, String), de.Value)
Next de
End Sub 'New
' Gets a String array that contains all the keys in the collection.
Public ReadOnly Property AllKeys() As String()
Get
Return Me.BaseGetAllKeys()
End Get
End Property
' Gets an Object array that contains all the values in the collection.
Public ReadOnly Property AllValues() As Array
Get
Return Me.BaseGetAllValues()
End Get
End Property
' Gets a String array that contains all the values in the collection.
Public ReadOnly Property AllStringValues() As String()
Get
Return CType(Me.BaseGetAllValues(GetType(String)), String())
End Get
End Property
End Class 'MyCollection
Public Class SamplesNameObjectCollectionBase
Public Shared Sub Main()
' Creates and initializes a new MyCollection instance.
Dim d As New ListDictionary()
d.Add("red", "apple")
d.Add("yellow", "banana")
d.Add("green", "pear")
Dim myCol As New MyCollection(d)
Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count)
PrintKeysAndValues(myCol)
' Displays the list of keys.
Console.WriteLine("The list of keys:")
Dim s As String
For Each s In myCol.AllKeys
Console.WriteLine(" {0}", s)
Next s
' Displays the list of values of type Object.
Console.WriteLine("The list of values (Object):")
Dim o As Object
For Each o In myCol.AllValues
Console.WriteLine(" {0}", o.ToString())
Next o
' Displays the list of values of type String.
Console.WriteLine("The list of values (String):")
For Each s In myCol.AllValues
Console.WriteLine(" {0}", s)
Next s
End Sub 'Main
Public Shared Sub PrintKeysAndValues(myCol As MyCollection)
Dim i As Integer
For i = 0 To myCol.Count - 1
Console.WriteLine("[{0}] : {1}, {2}", i, myCol(i).Key, myCol(i).Value)
Next i
End Sub 'PrintKeysAndValues
End Class 'SamplesNameObjectCollectionBase
'This code produces the following output.
'
'Initial state of the collection (Count = 3):
'[0] : red, apple
'[1] : yellow, banana
'[2] : green, pear
'The list of keys:
' red
' yellow
' green
'The list of values (Object):
' apple
' banana
' pear
'The list of values (String):
' apple
' banana
' pear