IList Schnittstelle

Definition

Stellt eine nicht generische Auflistung von Objekten dar, auf die einzeln über einen Index zugegriffen werden kann.

public interface class IList : System::Collections::ICollection
public interface IList : System.Collections.ICollection
[System.Runtime.InteropServices.ComVisible(true)]
public interface IList : System.Collections.ICollection
type IList = interface
    interface ICollection
    interface IEnumerable
[<System.Runtime.InteropServices.ComVisible(true)>]
type IList = interface
    interface ICollection
    interface IEnumerable
Public Interface IList
Implements ICollection
Abgeleitet
Attribute
Implementiert

Beispiele

Im folgenden Beispiel wird die Implementierung der IList -Schnittstelle zum Erstellen einer einfachen Liste mit fester Größe veranschaulicht.

using System;
using System.Collections;

class Program
{
    static void Main()
    {
        var test = new SimpleList();

        // Populate the List.
        Console.WriteLine("Populate the List");
        test.Add("one");
        test.Add("two");
        test.Add("three");
        test.Add("four");
        test.Add("five");
        test.Add("six");
        test.Add("seven");
        test.Add("eight");
        test.PrintContents();
        Console.WriteLine();

        // Remove elements from the list.
        Console.WriteLine("Remove elements from the list");
        test.Remove("six");
        test.Remove("eight");
        test.PrintContents();
        Console.WriteLine();

        // Add an element to the end of the list.
        Console.WriteLine("Add an element to the end of the list");
        test.Add("nine");
        test.PrintContents();
        Console.WriteLine();

        // Insert an element into the middle of the list.
        Console.WriteLine("Insert an element into the middle of the list");
        test.Insert(4, "number");
        test.PrintContents();
        Console.WriteLine();

        // Check for specific elements in the list.
        Console.WriteLine("Check for specific elements in the list");
        Console.WriteLine($"List contains \"three\": {test.Contains("three")}");
        Console.WriteLine($"List contains \"ten\": {test.Contains("ten")}");
    }
}

class SimpleList : IList
{
    private object[] _contents = new object[8];
    private int _count;

    public SimpleList()
    {
        _count = 0;
    }

    // IList Members
    public int Add(object value)
    {
        if (_count < _contents.Length)
        {
            _contents[_count] = value;
            _count++;

            return (_count - 1);
        }

        return -1;
    }

    public void Clear()
    {
        _count = 0;
    }

    public bool Contains(object value)
    {
        for (int i = 0; i < Count; i++)
        {
            if (_contents[i] == value)
            {
                return true;
            }
        }
        return false;
    }

    public int IndexOf(object value)
    {
        for (int i = 0; i < Count; i++)
        {
            if (_contents[i] == value)
            {
                return i;
            }
        }
        return -1;
    }

    public void Insert(int index, object value)
    {
        if ((_count + 1 <= _contents.Length) && (index < Count) && (index >= 0))
        {
            _count++;

            for (int i = Count - 1; i > index; i--)
            {
                _contents[i] = _contents[i - 1];
            }
            _contents[index] = value;
        }
    }

    public bool IsFixedSize
    {
        get
        {
            return true;
        }
    }

    public bool IsReadOnly
    {
        get
        {
            return false;
        }
    }

    public void Remove(object value)
    {
        RemoveAt(IndexOf(value));
    }

    public void RemoveAt(int index)
    {
        if ((index >= 0) && (index < Count))
        {
            for (int i = index; i < Count - 1; i++)
            {
                _contents[i] = _contents[i + 1];
            }
            _count--;
        }
    }

    public object this[int index]
    {
        get
        {
            return _contents[index];
        }
        set
        {
            _contents[index] = value;
        }
    }

    // ICollection members.

    public void CopyTo(Array array, int index)
    {
        for (int i = 0; i < Count; i++)
        {
            array.SetValue(_contents[i], index++);
        }
    }

    public int Count
    {
        get
        {
            return _count;
        }
    }

    public bool IsSynchronized
    {
        get
        {
            return false;
        }
    }

    // Return the current instance since the underlying store is not
    // publicly available.
    public object SyncRoot
    {
        get
        {
            return this;
        }
    }

    // IEnumerable Members

    public IEnumerator GetEnumerator()
    {
        // Refer to the IEnumerator documentation for an example of
        // implementing an enumerator.
        throw new NotImplementedException("The method or operation is not implemented.");
    }

    public void PrintContents()
    {
        Console.WriteLine($"List has a capacity of {_contents.Length} and currently has {_count} elements.");
        Console.Write("List contents:");
        for (int i = 0; i < Count; i++)
        {
            Console.Write($" {_contents[i]}");
        }
        Console.WriteLine();
    }
}

// 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
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($"List contains 'three': {myList.Contains("three")}")
        Console.WriteLine($"List contains 'ten': {myList.Contains("ten")}")
    End Sub
End Class

Public Class SimpleList
    Implements IList

    Private _contents(7) 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 Then
            _contents(_count) = value
            _count += 1

            Return _count - 1
        End If

        Return -1
    End Function

    Public Sub Clear() Implements IList.Clear
        _count = 0
    End Sub

    Public Function Contains(ByVal value As Object) As Boolean Implements IList.Contains
        For i As Integer = 0 To Count - 1
            If _contents(i) = value Then Return True
        Next

        Return False
    End Function

    Public Function IndexOf(ByVal value As Object) As Integer Implements IList.IndexOf
        For i As Integer = 0 To Count - 1
            If _contents(i) = value Then Return i
        Next
        Return -1
    End Function

    Public Sub Insert(ByVal index As Integer, ByVal value As Object) Implements IList.Insert

        If _count + 1 <= _contents.Length AndAlso index < Count AndAlso index >= 0 Then
            _count += 1

            For i As Integer = Count - 1 To index Step -1
                _contents(i) = _contents(i - 1)
            Next
            _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 AndAlso index < Count Then
            for i As Integer = index To Count - 2
                _contents(i) = _contents(i + 1)
            Next
            _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
        For i As Integer = 0 To Count - 1
            array.SetValue(_contents(i), index)
            index += 1
        Next
    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 NotImplementedException("The method or operation is not implemented.")
    End Function

    Public Sub PrintContents()
        Console.WriteLine($"List has a capacity of {_contents.Length} and currently has {_count} elements.")
        Console.Write("List contents:")

        For i As Integer = 0 To Count - 1
            Console.Write($" {_contents(i)}")
        Next

        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

Hinweise

IList ist ein Nachfolger der ICollection -Schnittstelle und die Basisschnittstelle aller nicht generischen Listen. IList -Implementierungen lassen sich in drei Kategorien unterteilen: schreibgeschützt, mit fester Größe und variabler Größe. Ein IList schreibgeschützter kann nicht geändert werden. Eine feste Größe IList lässt das Hinzufügen oder Entfernen von Elementen nicht zu, ermöglicht jedoch die Änderung vorhandener Elemente. Eine variable Größe IList ermöglicht das Hinzufügen, Entfernen und Ändern von Elementen.

Die generische Version dieser Schnittstelle finden Sie unter System.Collections.Generic.IList<T> .

Eigenschaften

Count

Ruft die Anzahl der Elemente ab, die in ICollection enthalten sind.

(Geerbt von ICollection)
IsFixedSize

Ruft einen Wert ab, der angibt, ob das IList eine feste Größe aufweist.

IsReadOnly

Ruft einen Wert ab, der angibt, ob das IList schreibgeschützt ist.

IsSynchronized

Ruft einen Wert ab, der angibt, ob der Zugriff auf die ICollection synchronisiert (threadsicher) ist.

(Geerbt von ICollection)
Item[Int32]

Ruft das Element am angegebenen Index ab oder legt dieses fest.

SyncRoot

Ruft ein Objekt ab, mit dem der Zugriff auf ICollection synchronisiert werden kann.

(Geerbt von ICollection)

Methoden

Add(Object)

Fügt der IList ein Element hinzu.

Clear()

Entfernt alle Elemente aus IList.

Contains(Object)

Ermittelt, ob die IList einen bestimmten Wert enthält.

CopyTo(Array, Int32)

Kopiert die Elemente der ICollection in ein Array, beginnend bei einem bestimmten Array-Index.

(Geerbt von ICollection)
GetEnumerator()

Gibt einen Enumerator zurück, der eine Auflistung durchläuft.

(Geerbt von IEnumerable)
IndexOf(Object)

Bestimmt den Index eines bestimmten Elements in der IList.

Insert(Int32, Object)

Fügt am angegebenen Index ein Element in die IList ein.

Remove(Object)

Entfernt das erste Vorkommen eines angegebenen Objekts aus der IList.

RemoveAt(Int32)

Entfernt das IList-Element am angegebenen Index.

Erweiterungsmethoden

Cast<TResult>(IEnumerable)

Wandelt die Elemente eines IEnumerable in den angegebenen Typ um

OfType<TResult>(IEnumerable)

Filtert die Elemente eines IEnumerable anhand eines angegebenen Typs

AsParallel(IEnumerable)

Ermöglicht die Parallelisierung einer Abfrage.

AsQueryable(IEnumerable)

Konvertiert einen IEnumerable in einen IQueryable.

Gilt für

Siehe auch