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
' Removes an entry with the specified key from the collection.
Overloads Public Sub Remove(key As [String])
Me.BaseRemove(key)
End Sub 'Remove
' Removes an entry in the specified index from the collection.
Overloads Public Sub Remove(index As Integer)
Me.BaseRemoveAt(index)
End Sub 'Remove
End Class 'MyCollection
Public Class SamplesNameObjectCollectionBase
Public Shared Sub Main()
' Creates and initializes a new MyCollection instance.
Dim d = 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)
' Removes an element at a specific index.
myCol.Remove(1)
Console.WriteLine("After removing the element at index 1 (Count = {0}):", myCol.Count)
PrintKeysAndValues(myCol)
' Removes an element with a specific key.
myCol.Remove("red")
Console.WriteLine("After removing the element with the key ""red"" (Count = {0}):", myCol.Count)
PrintKeysAndValues(myCol)
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
'After removing the element at index 1 (Count = 2):
'[0] : red, apple
'[1] : green, pear
'After removing the element with the key "red" (Count = 1):
'[0] : green, pear