ArrayList.Synchronized Method (IList)

 

Returns an IList wrapper that is synchronized (thread safe).

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

<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization := True)>
Public Shared Function Synchronized (
	list As IList
) As IList

Parameters

list
Type: System.Collections.IList

The IList to synchronize.

Return Value

Type: System.Collections.IList

An IList wrapper that is synchronized (thread safe).

Exception Condition
ArgumentNullException

list is null.

To guarantee the thread safety of the ArrayList, all operations must be done through this wrapper.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration.

Dim myCollection As New ArrayList()

SyncLock myCollection.SyncRoot
    For Each item As Object In myCollection
        ' Insert your code here.
    Next item
End SyncLock

This method is an O(1) operation.

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
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