Hashtable.Synchronized(Hashtable) 方法

定义

返回 Hashtable 的同步(线程安全)包装。Returns a synchronized (thread-safe) wrapper for the Hashtable.

public:
 static System::Collections::Hashtable ^ Synchronized(System::Collections::Hashtable ^ table);
public static System.Collections.Hashtable Synchronized (System.Collections.Hashtable table);
static member Synchronized : System.Collections.Hashtable -> System.Collections.Hashtable
Public Shared Function Synchronized (table As Hashtable) As Hashtable

参数

table
Hashtable

要同步的 HashtableThe Hashtable to synchronize.

返回

Hashtable 的同步(线程安全)包装。A synchronized (thread-safe) wrapper for the Hashtable.

异常

tablenulltable is null.

示例

下面的示例演示如何同步 Hashtable,确定 @no__t 是否同步,并使用同步 HashtableThe following example shows how to synchronize a Hashtable, determine if a Hashtable is synchronized, and use a synchronized Hashtable.

#using <system.dll>

using namespace System;
using namespace System::Collections;
void main()
{
   
   // Creates and initializes a new Hashtable.
   Hashtable^ myHT = gcnew Hashtable;
   myHT->Add( (int^)0, "zero" );
   myHT->Add( 1, "one" );
   myHT->Add( 2, "two" );
   myHT->Add( 3, "three" );
   myHT->Add( 4, "four" );
   
   // Creates a synchronized wrapper around the Hashtable.
   Hashtable^ mySyncdHT = Hashtable::Synchronized( myHT );
   
   // Displays the sychronization status of both Hashtables.
   Console::WriteLine( "myHT is {0}.", myHT->IsSynchronized ? (String^)"synchronized" : "not synchronized" );
   Console::WriteLine( "mySyncdHT is {0}.", mySyncdHT->IsSynchronized ? (String^)"synchronized" : "not synchronized" );
}

/*
 This code produces the following output.

 myHT is not synchronized.
 mySyncdHT is synchronized.
 */
using System;
using System.Collections;
public class SamplesHashtable
{

   public static void Main()
   {
      // Creates and initializes a new Hashtable.
      var myHT = new Hashtable();
      myHT.Add(0, "zero");
      myHT.Add(1, "one");
      myHT.Add(2, "two");
      myHT.Add(3, "three");
      myHT.Add(4, "four");

      // Creates a synchronized wrapper around the Hashtable.
      Hashtable mySyncdHT = Hashtable.Synchronized(myHT);

      // Displays the sychronization status of both Hashtables.
      Console.WriteLine("myHT is {0}.", myHT.IsSynchronized ? "synchronized" : "not synchronized" );
      Console.WriteLine("mySyncdHT is {0}.", mySyncdHT.IsSynchronized ? "synchronized" : "not synchronized");
   }
}
/* 
This code produces the following output.

myHT is not synchronized.
mySyncdHT is synchronized.
*/ 
Imports System.Collections

Public Class SamplesHashtable    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new Hashtable.
        Dim myHT As New Hashtable()
        myHT.Add(0, "zero")
        myHT.Add(1, "one")
        myHT.Add(2, "two")
        myHT.Add(3, "three")
        myHT.Add(4, "four")
        
        ' Creates a synchronized wrapper around the Hashtable.
        Dim mySyncdHT As Hashtable = Hashtable.Synchronized(myHT)
        
        ' Displays the sychronization status of both Hashtables.
        Dim msg As String = If(myHT.IsSynchronized, "synchronized", "not synchronized")
        Console.WriteLine($"myHT is {msg}.")
        msg = If(mySyncdHT.IsSynchronized, "synchronized", "not synchronized")
        Console.WriteLine($"mySyncdHT is {msg}.")
    End Sub
End Class

' This code produces the following output.
' 
' myHT is not synchronized.
' mySyncdHT is synchronized. 

注解

@No__t-0 方法对于多个读取器和编写器是线程安全的。The Synchronized method is thread safe for multiple readers and writers. 而且,同步包装将确保一次只写入一个编写器。Furthermore, the synchronized wrapper ensures that there is only one writer writing at a time.

枚举整个集合本质上不是一个线程安全的过程。Enumerating through a collection is intrinsically not a thread-safe procedure. 即使某个集合已同步,其他线程仍可以修改该集合,这会导致枚举数引发异常。Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. 若要确保枚举过程中的线程安全性,可以在整个枚举期间锁定集合,或者捕获由其他线程进行的更改所导致的异常。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.

下面的代码示例演示如何在整个枚举过程中使用 SyncRoot 锁定集合:The following code example shows how to lock the collection using the SyncRoot during the entire enumeration:

Hashtable^ myCollection = gcnew Hashtable();
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);
    }
}
var myCollection = new Hashtable();
lock (myCollection.SyncRoot)
{
    foreach (object item in myCollection)
    {
        // Insert your code here.
    }
}
Dim myCollection As New Hashtable()
SyncLock myCollection.SyncRoot
    For Each item In myCollection
        ' Insert your code here.
    Next
End SyncLock

此方法是 @no__t 0 操作。This method is an O(1) operation.

适用于

另请参阅