ArrayList.SyncRoot ArrayList.SyncRoot ArrayList.SyncRoot ArrayList.SyncRoot Property

Definition

Gets an object that can be used to synchronize access to the ArrayList.

public:
 virtual property System::Object ^ SyncRoot { System::Object ^ get(); };
public virtual object SyncRoot { get; }
member this.SyncRoot : obj
Public Overridable ReadOnly Property SyncRoot As Object

Property Value

An object that can be used to synchronize access to the ArrayList.

Implements

Examples

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

ArrayList^ myCollection = gcnew ArrayList();
bool lockTaken = false;
try
{
    Monitor::Enter(myCollection->SyncRoot, lockTaken);
    for each (Object^ item in myCollection);
    {
        // Insert your code here.
    }
}
finally
{
    if (lockTaken)
    {
        Monitor::Exit(myCollection->SyncRoot);
    }
}
ArrayList myCollection = new ArrayList();

lock(myCollection.SyncRoot)
{
    foreach (object item in myCollection)
    {
        // Insert your code here.
    }
}
Dim myCollection As New ArrayList()

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

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

Remarks

To create a synchronized version of the ArrayList, use the Synchronized method. However, derived classes can provide their own synchronized version of the ArrayList using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot of the ArrayList, not directly on the ArrayList. This ensures proper operation of collections that are derived from other objects. Specifically, it maintains proper synchronization with other threads that might be simultaneously modifying the ArrayList object.

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.

Applies to

See also