IList Interface
Assembly: mscorlib (in mscorlib.dll)
'Declaration <ComVisibleAttribute(True)> _ Public Interface IList Inherits ICollection, IEnumerable 'Usage Dim instance As IList
/** @attribute ComVisibleAttribute(true) */ public interface IList extends ICollection, IEnumerable
ComVisibleAttribute(true) public interface IList extends ICollection, IEnumerable
Not applicable.
IList is a descendant of the ICollection interface and is the base interface of all non-generic lists. IList implementations fall into three categories: read-only, fixed-size, and variable-size. A read-only IList cannot be modified. A fixed-size IList does not allow the addition or removal of elements, but it allows the modification of existing elements. A variable-size IList allows the addition, removal, and modification of elements.
For the generic version of this interface, see System.Collections.Generic.IList.
The following example demonstrates the implementation of the IList interface to create a simple list, fixed-size list.
Imports System Imports System.Collections Public Class Program Shared Sub Main() Dim myList As New SimpleList() ' Populate the List Console.WriteLine("Populate the List") myList.Add("one") myList.Add("two") myList.Add("three") myList.Add("four") myList.Add("five") myList.Add("six") myList.Add("seven") myList.Add("eight") myList.PrintContents() Console.WriteLine() ' Remove elements from the list Console.WriteLine("Remove elements from the list") myList.Remove("six") myList.Remove("eight") myList.PrintContents() Console.WriteLine() ' Add an element to the end of the list Console.WriteLine("Add an element to the end of the list") myList.Add("nine") myList.PrintContents() Console.WriteLine() ' Insert an element into the middle of the list Console.WriteLine("Insert an element into the middle of the list") myList.Insert(4, "number") myList.PrintContents() Console.WriteLine() ' Check for specific elements in the list Console.WriteLine("Check for specific elements in the list") Console.WriteLine("List contains 'three': {0}", myList.Contains("three")) Console.WriteLine("List contains 'ten': {0}", myList.Contains("ten")) End Sub End Class ' class Program Public Class SimpleList Implements IList Private _contents(8) As Object Private _count As Integer Public Sub New() _count = 0 End Sub ' IList Members Public Function Add(ByVal value As Object) As Integer Implements IList.Add If (_count < _contents.Length - 1) Then _contents(_count) = value _count = _count + 1 Return (_count - 1) Else Return -1 End If End Function Public Sub Clear() Implements IList.Clear _count = 0 End Sub Public Function Contains(ByVal value As Object) As Boolean Implements IList.Contains Dim inList As Boolean = False Dim i As Integer For i = 0 To Count If _contents(i) = value Then inList = True Exit For End If Next i Return inList End Function Public Function IndexOf(ByVal value As Object) As Integer Implements IList.IndexOf Dim itemIndex As Integer = -1 Dim i As Integer For i = 0 To Count If _contents(i) = value Then itemIndex = i Exit For End If Next i Return itemIndex End Function Public Sub Insert(ByVal index As Integer, ByVal value As Object) Implements IList.Insert If (_count + 1) <= (_contents.Length - 1) And (index < Count) And (index >= 0) Then _count = _count + 1 Dim i As Integer For i = Count - 1 To index _contents(i) = _contents(i - 1) Next i _contents(index) = value End If End Sub Public ReadOnly Property IsFixedSize() As Boolean Implements IList.IsFixedSize Get Return True End Get End Property Public ReadOnly Property IsReadOnly() As Boolean Implements IList.IsReadOnly Get Return False End Get End Property Public Sub Remove(ByVal value As Object) Implements IList.Remove RemoveAt(IndexOf(value)) End Sub Public Sub RemoveAt(ByVal index As Integer) Implements IList.RemoveAt If index >= 0 And index < Count Then Dim i As Integer For i = index To Count - 1 _contents(i) = _contents(i + 1) Next i _count = _count - 1 End If End Sub Public Property Item(ByVal index As Integer) As Object Implements IList.Item Get Return _contents(index) End Get Set(ByVal value As Object) _contents(index) = value End Set End Property ' ICollection Members Public Sub CopyTo(ByVal array As Array, ByVal index As Integer) Implements ICollection.CopyTo Dim j As Integer = index Dim i As Integer For i = 0 To Count array.SetValue(_contents(i), j) j = j + 1 Next i End Sub Public ReadOnly Property Count() As Integer Implements ICollection.Count Get Return _count End Get End Property Public ReadOnly Property IsSynchronized() As Boolean Implements ICollection.IsSynchronized Get Return False End Get End Property ' Return the current instance since the underlying store is not ' publicly available. Public ReadOnly Property SyncRoot() As Object Implements ICollection.SyncRoot Get Return Me End Get End Property ' IEnumerable Members Public Function GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator ' Refer to the IEnumerator documentation for an example of ' implementing an enumerator. Throw New Exception("The method or operation is not implemented.") End Function Public Sub PrintContents() Console.WriteLine("List has a capacity of {0} and currently has {1} elements.", _contents.Length - 1, _count) Console.Write("List contents:") Dim i As Integer For i = 0 To Count Console.Write(" {0}", _contents(i)) Next i Console.WriteLine() End Sub End Class ' This code produces output similar to the following: ' Populate the List: ' List has a capacity of 8 and currently has 8 elements. ' List contents: one two three four five six seven eight ' ' Remove elements from the list: ' List has a capacity of 8 and currently has 6 elements. ' List contents: one two three four five seven ' ' Add an element to the end of the list: ' List has a capacity of 8 and currently has 7 elements. ' List contents: one two three four five seven nine ' ' Insert an element into the middle of the list: ' List has a capacity of 8 and currently has 8 elements. ' List contents: one two three four number five seven nine ' ' Check for specific elements in the list: ' List contains "three": True ' List contains "ten": False
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.