ArrayList.TrimToSize ArrayList.TrimToSize ArrayList.TrimToSize ArrayList.TrimToSize Method

Definition

Legt die Kapazität auf die Anzahl der tatsächlich in der ArrayList enthaltenen Elemente fest.Sets the capacity to the actual number of elements in the ArrayList.

public:
 virtual void TrimToSize();
public virtual void TrimToSize ();
abstract member TrimToSize : unit -> unit
override this.TrimToSize : unit -> unit
Public Overridable Sub TrimToSize ()

Ausnahmen

ArrayList ist schreibgeschützt.The ArrayList is read-only.

- oder --or- ArrayList hat eine feste Größe.The ArrayList has a fixed size.

Beispiele

Im folgenden Codebeispiel wird gezeigt, wie Sie die nicht verwendeten Teile der ArrayList kürzen und die Werte von ArrayList löschen.The following code example shows how to trim the unused portions of the ArrayList and how to clear the values of the ArrayList.

using namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myList );
int main()
{
   
   // Creates and initializes a new ArrayList.
   ArrayList^ myAL = gcnew ArrayList;
   myAL->Add( "The" );
   myAL->Add( "quick" );
   myAL->Add( "brown" );
   myAL->Add( "fox" );
   myAL->Add( "jumps" );
   
   // 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 );
}

void PrintValues( IEnumerable^ myList )
{
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::Write( "   {0}", obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 Initially,
    Count    : 5
    Capacity : 16
    Values:    The    quick    brown    fox    jumps
 After TrimToSize,
    Count    : 5
    Capacity : 5
    Values:    The    quick    brown    fox    jumps
 After Clear,
    Count    : 0
    Capacity : 5
    Values:
 After the second TrimToSize,
    Count    : 0
    Capacity : 16
    Values:
 */
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( "jumps" );

      // 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    jumps
After TrimToSize,
   Count    : 5
   Capacity : 5
   Values:    The    quick    brown    fox    jumps
After Clear,
   Count    : 0
   Capacity : 5
   Values:
After the second TrimToSize,
   Count    : 0
   Capacity : 16
   Values:
*/ 
Imports System.Collections

Public Class SamplesArrayList    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new ArrayList.
        Dim myAL As New ArrayList()
        myAL.Add("The")
        myAL.Add("quick")
        myAL.Add("brown")
        myAL.Add("fox")
        myAL.Add("jumps")
        
        ' 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)
    End Sub

    Public Shared Sub PrintValues(myList As IEnumerable)
        Dim obj As [Object]
        For Each obj In  myList
            Console.Write("   {0}", obj)
        Next obj
        Console.WriteLine()
    End Sub

End Class

' This code produces the following output.
' 
' Initially,
'    Count    : 5
'    Capacity : 16
'    Values:    The    quick    brown    fox    jumps
' After TrimToSize,
'    Count    : 5
'    Capacity : 5
'    Values:    The    quick    brown    fox    jumps
' After Clear,
'    Count    : 0
'    Capacity : 5
'    Values:
' After the second TrimToSize,
'    Count    : 0
'    Capacity : 16
'    Values:

Hinweise

Diese Methode kann verwendet werden, um den Arbeitsspeicher Aufwand einer Sammlung zu minimieren, wenn der Auflistung keine neuen Elemente hinzugefügt werden.This method can be used to minimize a collection's memory overhead if no new elements will be added to the collection.

Rufen Sie die Clear-Methode auf, bevor Sie TrimToSize aufrufen, um ein ArrayList auf den ursprünglichen Zustand zurückzusetzen.To reset a ArrayList to its initial state, call the Clear method before calling TrimToSize. Wenn Sie einen leeren ArrayList kürzen, wird die Kapazität des ArrayList auf die Standardkapazität festgelegt.Trimming an empty ArrayList sets the capacity of the ArrayList to the default capacity.

Bei dieser Methode handelt es sich um einen O(n)-Vorgang, bei dem n Count ist.This method is an O(n) operation, where n is Count.

Gilt für:

Siehe auch