Queue.IsSynchronized 屬性
重要
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取得值，這個值表示對 Queue 的存取是否同步 (安全執行緒)。
public:
virtual property bool IsSynchronized { bool get(); };public virtual bool IsSynchronized { get; }member this.IsSynchronized : boolPublic Overridable ReadOnly Property IsSynchronized As Boolean如果 true 的存取為同步 (安全執行緒)，則為 Queue，否則為 false。 預設為 false。
下列程式代碼範例示範如何在整個列舉期間使用 SyncRoot 鎖定集合。 擷取此屬性的值是作業 O(1) 。
Queue^ myCollection = gcnew Queue();
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);
}
}
Queue myCollection = new Queue();
lock (myCollection.SyncRoot)
{
foreach (object item in myCollection)
{
// Insert your code here.
}
}
Dim myCollection As New Queue()
SyncLock myCollection.SyncRoot
For Each item In myCollection
' Insert your code here.
Next item
End SyncLock
下列範例示範如何同步處理 Queue、判斷 是否已 Queue 同步處理 ，以及使用已同步處理的 Queue。
#using <system.dll>
using namespace System;
using namespace System::Collections;
int main()
{
// Creates and initializes a new Queue.
Queue^ myQ = gcnew Queue;
myQ->Enqueue( "The" );
myQ->Enqueue( "quick" );
myQ->Enqueue( "brown" );
myQ->Enqueue( "fox" );
// Creates a synchronized wrapper around the Queue.
Queue^ mySyncdQ = Queue::Synchronized( myQ );
// Displays the sychronization status of both Queues.
Console::WriteLine( "myQ is {0}.", myQ->IsSynchronized ? (String^)"synchronized" : "not synchronized" );
Console::WriteLine( "mySyncdQ is {0}.", mySyncdQ->IsSynchronized ? (String^)"synchronized" : "not synchronized" );
}
/*
This code produces the following output.
myQ is not synchronized.
mySyncdQ is synchronized.
*/
using System;
using System.Collections;
public class SamplesQueue
{
public static void Main()
{
// Creates and initializes a new Queue.
Queue myQ = new Queue();
myQ.Enqueue("The");
myQ.Enqueue("quick");
myQ.Enqueue("brown");
myQ.Enqueue("fox");
// Creates a synchronized wrapper around the Queue.
Queue mySyncdQ = Queue.Synchronized(myQ);
// Displays the sychronization status of both Queues.
Console.WriteLine("myQ is {0}.", myQ.IsSynchronized ? "synchronized" : "not synchronized");
Console.WriteLine("mySyncdQ is {0}.", mySyncdQ.IsSynchronized ? "synchronized" : "not synchronized");
}
}
/*
This code produces the following output.
myQ is not synchronized.
mySyncdQ is synchronized.
*/
Imports System.Collections
Public Class SamplesQueue
Public Shared Sub Main()
' Creates and initializes a new Queue.
Dim myQ As New Queue()
myQ.Enqueue("The")
myQ.Enqueue("quick")
myQ.Enqueue("brown")
myQ.Enqueue("fox")
' Creates a synchronized wrapper around the Queue.
Dim mySyncdQ As Queue = Queue.Synchronized(myQ)
' Displays the sychronization status of both Queues.
Dim msg As String
If myQ.IsSynchronized Then
msg = "synchronized"
Else
msg = "not synchronized"
End If
Console.WriteLine("myQ is {0}.", msg)
If mySyncdQ.IsSynchronized Then
msg = "synchronized"
Else
msg = "not synchronized"
End If
Console.WriteLine("mySyncdQ is {0}.", msg)
End Sub
End Class
' This code produces the following output.
'
' myQ is not synchronized.
' mySyncdQ is synchronized.
若要保證的 Queue線程安全性，所有作業都必須透過 方法傳 Synchronized 回的包裝函式來完成。
透過集合進行列舉在本質上並非安全執行緒程序。 即使集合經過同步化，其他的執行緒仍可修改該集合，使列舉值擲回例外狀況。 若要保證列舉過程的執行緒安全，您可以在整個列舉過程中鎖定集合，或攔截由其他執行緒的變更所造成的例外狀況。
