ArrayList.IsFixedSize Eigenschaft

Definition

Namespace:

System.Collections

Assembly:

System.Runtime.dll

Quelle:

ArrayList.cs

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

public:
 virtual property bool IsFixedSize { bool get(); };

public virtual bool IsFixedSize { get; }

member this.IsFixedSize : bool

Public Overridable ReadOnly Property IsFixedSize As Boolean

Eigenschaftswert

Boolean

Ist true, wenn die ArrayList eine feste Größe aufweist, andernfalls false. Der Standardwert ist false.

Implementiert

IsFixedSize

Beispiele

Das folgende Codebeispiel zeigt, wie Sie einen Wrapper mit fester Größe um einen ArrayListerstellen.

using namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myList, char mySeparator );
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" );
   myAL->Add( "over" );
   myAL->Add( "the" );
   myAL->Add( "lazy" );
   myAL->Add( "dog" );
   
   // Create a fixed-size wrapper around the ArrayList.
   ArrayList^ myFixedSizeAL = ArrayList::FixedSize( myAL );
   
   // Display whether the ArrayLists have a fixed size or not.
   Console::WriteLine( "myAL {0}.", myAL->IsFixedSize ? (String^)"has a fixed size" : "does not have a fixed size" );
   Console::WriteLine( "myFixedSizeAL {0}.", myFixedSizeAL->IsFixedSize ? (String^)"has a fixed size" : "does not have a fixed size" );
   Console::WriteLine();
   
   // Display both ArrayLists.
   Console::WriteLine( "Initially," );
   Console::Write( "Standard  :" );
   PrintValues( myAL, ' ' );
   Console::Write( "Fixed size:" );
   PrintValues( myFixedSizeAL, ' ' );
   
   // Sort is allowed in the fixed-size ArrayList.
   myFixedSizeAL->Sort();
   
   // Display both ArrayLists.
   Console::WriteLine( "After Sort," );
   Console::Write( "Standard  :" );
   PrintValues( myAL, ' ' );
   Console::Write( "Fixed size:" );
   PrintValues( myFixedSizeAL, ' ' );
   
   // Reverse is allowed in the fixed-size ArrayList.
   myFixedSizeAL->Reverse();
   
   // Display both ArrayLists.
   Console::WriteLine( "After Reverse," );
   Console::Write( "Standard  :" );
   PrintValues( myAL, ' ' );
   Console::Write( "Fixed size:" );
   PrintValues( myFixedSizeAL, ' ' );
   
   // Add an element to the standard ArrayList.
   myAL->Add( "AddMe" );
   
   // Display both ArrayLists.
   Console::WriteLine( "After adding to the standard ArrayList," );
   Console::Write( "Standard  :" );
   PrintValues( myAL, ' ' );
   Console::Write( "Fixed size:" );
   PrintValues( myFixedSizeAL, ' ' );
   Console::WriteLine();
   
   // Adding or inserting elements to the fixed-size ArrayList throws an exception.
   try
   {
      myFixedSizeAL->Add( "AddMe2" );
   }
   catch ( Exception^ myException ) 
   {
      Console::WriteLine( "Exception: {0}", myException );
   }

   try
   {
      myFixedSizeAL->Insert( 3, "InsertMe" );
   }
   catch ( Exception^ myException ) 
   {
      Console::WriteLine( "Exception: {0}", myException );
   }

}

void PrintValues( IEnumerable^ myList, char mySeparator )
{
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::Write( "{0}{1}", mySeparator, obj );
   }

   Console::WriteLine();
}

/*
 This code produces the following output.
 
 myAL does not have a fixed size.
 myFixedSizeAL has a fixed size.

 Initially,
 Standard  : The quick brown fox jumps over the lazy dog
 Fixed size: The quick brown fox jumps over the lazy dog
 After Sort,
 Standard  : brown dog fox jumps lazy over quick the The
 Fixed size: brown dog fox jumps lazy over quick the The
 After Reverse,
 Standard  : The the quick over lazy jumps fox dog brown
 Fixed size: The the quick over lazy jumps fox dog brown
 After adding to the standard ArrayList,
 Standard  : The the quick over lazy jumps fox dog brown AddMe
 Fixed size: The the quick over lazy jumps fox dog brown AddMe

 Exception: System.NotSupportedException: Collection was of a fixed size.
    at System.Collections.FixedSizeArrayList.Add(Object obj)
    at SamplesArrayList.Main()
 Exception: System.NotSupportedException: Collection was of a fixed size.
    at System.Collections.FixedSizeArrayList.Insert(Int32 index, Object obj)
    at SamplesArrayList.Main()

 */

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" );
      myAL.Add( "over" );
      myAL.Add( "the" );
      myAL.Add( "lazy" );
      myAL.Add( "dog" );

      // Create a fixed-size wrapper around the ArrayList.
      ArrayList myFixedSizeAL = ArrayList.FixedSize( myAL );

      // Display whether the ArrayLists have a fixed size or not.
      Console.WriteLine( "myAL {0}.", myAL.IsFixedSize ? "has a fixed size" : "does not have a fixed size" );
      Console.WriteLine( "myFixedSizeAL {0}.", myFixedSizeAL.IsFixedSize ? "has a fixed size" : "does not have a fixed size" );
      Console.WriteLine();

      // Display both ArrayLists.
      Console.WriteLine( "Initially," );
      Console.Write( "Standard  :" );
      PrintValues( myAL, ' ' );
      Console.Write( "Fixed size:" );
      PrintValues( myFixedSizeAL, ' ' );

      // Sort is allowed in the fixed-size ArrayList.
      myFixedSizeAL.Sort();

      // Display both ArrayLists.
      Console.WriteLine( "After Sort," );
      Console.Write( "Standard  :" );
      PrintValues( myAL, ' ' );
      Console.Write( "Fixed size:" );
      PrintValues( myFixedSizeAL, ' ' );

      // Reverse is allowed in the fixed-size ArrayList.
      myFixedSizeAL.Reverse();

      // Display both ArrayLists.
      Console.WriteLine( "After Reverse," );
      Console.Write( "Standard  :" );
      PrintValues( myAL, ' ' );
      Console.Write( "Fixed size:" );
      PrintValues( myFixedSizeAL, ' ' );

      // Add an element to the standard ArrayList.
      myAL.Add( "AddMe" );

      // Display both ArrayLists.
      Console.WriteLine( "After adding to the standard ArrayList," );
      Console.Write( "Standard  :" );
      PrintValues( myAL, ' ' );
      Console.Write( "Fixed size:" );
      PrintValues( myFixedSizeAL, ' ' );
      Console.WriteLine();

      // Adding or inserting elements to the fixed-size ArrayList throws an exception.
      try  {
         myFixedSizeAL.Add( "AddMe2" );
      } catch ( Exception myException )  {
         Console.WriteLine("Exception: " + myException.ToString());
      }
      try  {
         myFixedSizeAL.Insert( 3, "InsertMe" );
      } catch ( Exception myException )  {
         Console.WriteLine("Exception: " + myException.ToString());
      }
   }

   public static void PrintValues( IEnumerable myList, char mySeparator )  {
      foreach ( Object obj in myList )
         Console.Write( "{0}{1}", mySeparator, obj );
      Console.WriteLine();
   }
}
/*
This code produces the following output.

myAL does not have a fixed size.
myFixedSizeAL has a fixed size.

Initially,
Standard  : The quick brown fox jumps over the lazy dog
Fixed size: The quick brown fox jumps over the lazy dog
After Sort,
Standard  : brown dog fox jumps lazy over quick the The
Fixed size: brown dog fox jumps lazy over quick the The
After Reverse,
Standard  : The the quick over lazy jumps fox dog brown
Fixed size: The the quick over lazy jumps fox dog brown
After adding to the standard ArrayList,
Standard  : The the quick over lazy jumps fox dog brown AddMe
Fixed size: The the quick over lazy jumps fox dog brown AddMe

Exception: System.NotSupportedException: Collection was of a fixed size.
   at System.Collections.FixedSizeArrayList.Add(Object obj)
   at SamplesArrayList.Main()
Exception: System.NotSupportedException: Collection was of a fixed size.
   at System.Collections.FixedSizeArrayList.Insert(int index, Object obj)
   at SamplesArrayList.Main()

*/

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")
        myAL.Add("over")
        myAL.Add("the")
        myAL.Add("lazy")
        myAL.Add("dog")
        
        ' Create a fixed-size wrapper around the ArrayList.
        Dim myFixedSizeAL As ArrayList = ArrayList.FixedSize(myAL)
        
        ' Display whether the ArrayLists have a fixed size or not.
        Dim msg As String
        If myAL.IsFixedSize Then
            msg = "has a fixed size"
        Else
            msg = "does not have a fixed size"
        End If
        Console.WriteLine("myAL {0}.", msg)
        If myFixedSizeAL.IsFixedSize Then
            msg = "has a fixed size"
        Else
            msg = "does not have a fixed size"
        End If
        Console.WriteLine("myFixedSizeAL {0}.", msg)
        Console.WriteLine()
        
        ' Display both ArrayLists.
        Console.WriteLine("Initially,")
        Console.Write("Standard  :")
        PrintValues(myAL, " "c)
        Console.Write("Fixed size:")
        PrintValues(myFixedSizeAL, " "c)
        
        ' Sort is allowed in the fixed-size ArrayList.
        myFixedSizeAL.Sort()
        
        ' Display both ArrayLists.
        Console.WriteLine("After Sort,")
        Console.Write("Standard  :")
        PrintValues(myAL, " "c)
        Console.Write("Fixed size:")
        PrintValues(myFixedSizeAL, " "c)
        
        ' Reverse is allowed in the fixed-size ArrayList.
        myFixedSizeAL.Reverse()
        
        ' Display both ArrayLists.
        Console.WriteLine("After Reverse,")
        Console.Write("Standard  :")
        PrintValues(myAL, " "c)
        Console.Write("Fixed size:")
        PrintValues(myFixedSizeAL, " "c)
        
        ' Add an element to the standard ArrayList.
        myAL.Add("AddMe")
        
        ' Display both ArrayLists.
        Console.WriteLine("After adding to the standard ArrayList,")
        Console.Write("Standard  :")
        PrintValues(myAL, " "c)
        Console.Write("Fixed size:")
        PrintValues(myFixedSizeAL, " "c)
        Console.WriteLine()
        
        ' Adding or inserting elements to the fixed-size ArrayList throws an exception.
        Try
            myFixedSizeAL.Add("AddMe2")
        Catch myException As Exception
            Console.WriteLine("Exception: " + myException.ToString())
        End Try
        Try
            myFixedSizeAL.Insert(3, "InsertMe")
        Catch myException As Exception
            Console.WriteLine("Exception: " + myException.ToString())
        End Try
    End Sub

    Public Shared Sub PrintValues(myList As IEnumerable, mySeparator As Char)
        Dim obj As [Object]
        For Each obj In  myList
            Console.Write("{0}{1}", mySeparator, obj)
        Next obj
        Console.WriteLine()
    End Sub

End Class


' This code produces the following output.
' 
' myAL does not have a fixed size.
' myFixedSizeAL has a fixed size.
' 
' Initially,
' Standard  : The quick brown fox jumps over the lazy dog
' Fixed size: The quick brown fox jumps over the lazy dog
' After Sort,
' Standard  : brown dog fox jumps lazy over quick the The
' Fixed size: brown dog fox jumps lazy over quick the The
' After Reverse,
' Standard  : The the quick over lazy jumps fox dog brown
' Fixed size: The the quick over lazy jumps fox dog brown
' After adding to the standard ArrayList,
' Standard  : The the quick over lazy jumps fox dog brown AddMe
' Fixed size: The the quick over lazy jumps fox dog brown AddMe
' 
' Exception: System.NotSupportedException: Collection was of a fixed size.
'    at System.Collections.FixedSizeArrayList.Add(Object obj)
'    at SamplesArrayList.Main()
' Exception: System.NotSupportedException: Collection was of a fixed size.
'    at System.Collections.FixedSizeArrayList.Insert(Int32 index, Object obj)
'    at SamplesArrayList.Main()

Hinweise

Eine Auflistung mit fester Größe lässt das Hinzufügen oder Entfernen von Elementen nach dem Erstellen der Auflistung nicht zu. Vorhandene Elemente können jedoch geändert werden.

Eine Auflistung mit einer festen Größe ist einfach eine Auflistung mit einem Wrapper, der das Hinzufügen und Entfernen von Elementen verhindert. Wenn daher Änderungen an der zugrunde liegenden Auflistung vorgenommen werden, einschließlich des Hinzufügens oder Entfernens von Elementen, spiegelt die Auflistung mit fester Größe diese Änderungen wider.

Das Abrufen des Werts dieser Eigenschaft ist ein O(1) Vorgang.