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ArrayList.Clear-Methode

Aktualisiert: November 2007

Entfernt alle Elemente aus der ArrayList.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)

public virtual void Clear()
public void Clear()
public function Clear()

Implementiert

IList.Clear()

AusnahmeBedingung
NotSupportedException

ArrayList ist schreibgeschützt.

- oder -

ArrayList hat eine feste Größe.

Count wird auf 0 (null) festgelegt, und Verweise auf andere Objekte von Elementen in der Auflistung werden ebenfalls freigegeben.

Capacity bleibt unverändert. Wenn die Kapazität von ArrayList zurückgesetzt werden soll, rufen Sie TrimToSize auf, oder legen Sie die Capacity-Eigenschaft direkt fest. Durch das Verkürzen einer leeren ArrayList wird die Kapazität der ArrayList auf die Standardkapazität festgelegt.

Diese Methode ist eine O(n)-Operation, wobei n der Count ist.

Im folgenden Codebeispiel wird veranschaulicht, wie nicht verwendete Bereiche von ArrayList verkürzt und die Werte in ArrayList gelöscht werden.

using System;
using System.Collections;
public class SamplesArrayList  {

   public static void Main()  {

      // Creates and initializes a new ArrayList.
      ArrayList myAL = new ArrayList();
      myAL.Add( "The" );
      myAL.Add( "quick" );
      myAL.Add( "brown" );
      myAL.Add( "fox" );
      myAL.Add( "jumped" );

      // Displays the count, capacity and values of the ArrayList.
      Console.WriteLine( "Initially," );
      Console.WriteLine( "   Count    : {0}", myAL.Count );
      Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
      Console.Write( "   Values:" );
      PrintValues( myAL );

      // Trim the ArrayList.
      myAL.TrimToSize();

      // Displays the count, capacity and values of the ArrayList.
      Console.WriteLine( "After TrimToSize," );
      Console.WriteLine( "   Count    : {0}", myAL.Count );
      Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
      Console.Write( "   Values:" );
      PrintValues( myAL );

      // Clear the ArrayList.
      myAL.Clear();

      // Displays the count, capacity and values of the ArrayList.
      Console.WriteLine( "After Clear," );
      Console.WriteLine( "   Count    : {0}", myAL.Count );
      Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
      Console.Write( "   Values:" );
      PrintValues( myAL );

      // Trim the ArrayList again.
      myAL.TrimToSize();

      // Displays the count, capacity and values of the ArrayList.
      Console.WriteLine( "After the second TrimToSize," );
      Console.WriteLine( "   Count    : {0}", myAL.Count );
      Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
      Console.Write( "   Values:" );
      PrintValues( myAL );
   }

   public static void PrintValues( IEnumerable myList )  {
      foreach ( Object obj in myList )
         Console.Write( "   {0}", obj );
      Console.WriteLine();
   }

}
/* 
This code produces the following output.

Initially,
   Count    : 5
   Capacity : 16
   Values:    The    quick    brown    fox    jumped
After TrimToSize,
   Count    : 5
   Capacity : 5
   Values:    The    quick    brown    fox    jumped
After Clear,
   Count    : 0
   Capacity : 5
   Values:
After the second TrimToSize,
   Count    : 0
   Capacity : 16
   Values:
*/ 


import System.*;
import System.Collections.*;

public class SamplesArrayList
{
    public static void main(String[] args)
    {
        // Creates and initializes a new ArrayList.
        ArrayList myAL = new ArrayList();

        myAL.Add("The");
        myAL.Add("quick");
        myAL.Add("brown");
        myAL.Add("fox");
        myAL.Add("jumped");

        // Displays the count, capacity and values of the ArrayList.
        Console.WriteLine("Initially,");
        Console.WriteLine("   Count    : {0}", (Int32)myAL.get_Count());
        Console.WriteLine("   Capacity : {0}", (Int32)myAL.get_Capacity());
        Console.Write("   Values:");
        PrintValues(myAL);

        // Trim the ArrayList.
        myAL.TrimToSize();

        // Displays the count, capacity and values of the ArrayList.
        Console.WriteLine("After TrimToSize,");
        Console.WriteLine("   Count    : {0}", (Int32)myAL.get_Count());
        Console.WriteLine("   Capacity : {0}", (Int32)myAL.get_Capacity());
        Console.Write("   Values:");
        PrintValues(myAL);

        // Clear the ArrayList.
        myAL.Clear();

        // Displays the count, capacity and values of the ArrayList.
        Console.WriteLine("After Clear,");
        Console.WriteLine("   Count    : {0}", (Int32)myAL.get_Count());
        Console.WriteLine("   Capacity : {0}", (Int32)myAL.get_Capacity());
        Console.Write("   Values:");
        PrintValues(myAL);

        // Trim the ArrayList again.
        myAL.TrimToSize();

        // Displays the count, capacity and values of the ArrayList.
        Console.WriteLine("After the second TrimToSize,");
        Console.WriteLine("   Count    : {0}", (Int32)myAL.get_Count());
        Console.WriteLine("   Capacity : {0}", (Int32)myAL.get_Capacity());
        Console.Write("   Values:");
        PrintValues(myAL);
    } //main

    public static void PrintValues(IEnumerable myList)
    {
        IEnumerator objMyEnum = myList.GetEnumerator();
        while (objMyEnum.MoveNext()) {
            Object obj = objMyEnum.get_Current();
            Console.Write("   {0}", obj);
        }
        Console.WriteLine();
    } //PrintValues
} //SamplesArrayList 
/* 
 This code produces the following output.

 Initially,
    Count    : 5
    Capacity : 16
    Values:    The    quick    brown    fox    jumped
 After TrimToSize,
    Count    : 5
    Capacity : 5
    Values:    The    quick    brown    fox    jumped
 After Clear,
    Count    : 0
    Capacity : 5
    Values:
 After the second TrimToSize,
    Count    : 0
    Capacity : 16
    Values:
 */


import System;
import System.Collections;


// Creates and initializes a new ArrayList.
var myAL : ArrayList = new ArrayList();
myAL.Add( "The" );
myAL.Add( "quick" );
myAL.Add( "brown" );
myAL.Add( "fox" );
myAL.Add( "jumped" );

// Displays the count, capacity and values of the ArrayList.
Console.WriteLine( "Initially," );
Console.WriteLine( "   Count    : {0}", myAL.Count );
Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
Console.Write( "   Values:" );
PrintValues( myAL );

// Trim the ArrayList.
myAL.TrimToSize();

// Displays the count, capacity and values of the ArrayList.
Console.WriteLine( "After TrimToSize," );
Console.WriteLine( "   Count    : {0}", myAL.Count );
Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
Console.Write( "   Values:" );
PrintValues( myAL );

// Clear the ArrayList.
myAL.Clear();

// Displays the count, capacity and values of the ArrayList.
Console.WriteLine( "After Clear," );
Console.WriteLine( "   Count    : {0}", myAL.Count );
Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
Console.Write( "   Values:" );
PrintValues( myAL );

// Trim the ArrayList again.
myAL.TrimToSize();

// Displays the count, capacity and values of the ArrayList.
Console.WriteLine( "After the second TrimToSize," );
Console.WriteLine( "   Count    : {0}", myAL.Count );
Console.WriteLine( "   Capacity : {0}", myAL.Capacity );
Console.Write( "   Values:" );
PrintValues( myAL );

function PrintValues( myList : IEnumerable)  {
   var myEnumerator : System.Collections.IEnumerator  = myList.GetEnumerator();
   while ( myEnumerator.MoveNext() )
      Console.Write( "\t{0}", myEnumerator.Current );
   Console.WriteLine();
}
 /* 
 This code produces the following output.

 Initially,
    Count    : 5
    Capacity : 16
    Values:    The    quick    brown    fox    jumped
 After TrimToSize,
    Count    : 5
    Capacity : 5
    Values:    The    quick    brown    fox    jumped
 After Clear,
    Count    : 0
    Capacity : 5
    Values:
 After the second TrimToSize,
    Count    : 0
    Capacity : 16
    Values:
 */ 


Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile für Smartphone, Windows Mobile für Pocket PC, Xbox 360

.NET Framework und .NET Compact Framework unterstützen nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen für .NET Framework.

.NET Framework

Unterstützt in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 3.5, 2.0, 1.0

XNA Framework

Unterstützt in: 2.0, 1.0

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