ArrayList.IsFixedSize Property

Gets a value indicating whether the ArrayList has a fixed size.

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

'Declaration
Public Overridable ReadOnly Property IsFixedSize As Boolean

Property Value

Type: System.Boolean
true if the ArrayList has a fixed size; otherwise, false. The default is false.

Implements

IList.IsFixedSize

A collection with a fixed size does not allow the addition or removal of elements after the collection is created, but it allows the modification of existing elements.

A collection with a fixed size is simply a collection with a wrapper that prevents adding and removing elements; therefore, if changes are made to the underlying collection, including the addition or removal of elements, the fixed-size collection reflects those changes.

Retrieving the value of this property is an O(1) operation.

The following code example shows how to create a fixed-size wrapper around an ArrayList.

Imports System
Imports System.Collections
Imports Microsoft.VisualBasic

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("jumped")
        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 'Main

    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 'PrintValues

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 jumped over the lazy dog 
' Fixed size: The quick brown fox jumped over the lazy dog 
' After Sort, 
' Standard  : brown dog fox jumped lazy over quick the The 
' Fixed size: brown dog fox jumped lazy over quick the The 
' After Reverse, 
' Standard  : The the quick over lazy jumped fox dog brown 
' Fixed size: The the quick over lazy jumped fox dog brown 
' After adding to the standard ArrayList, 
' Standard  : The the quick over lazy jumped fox dog brown AddMe 
' Fixed size: The the quick over lazy jumped 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()

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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