IAsyncResult.IsCompleted IAsyncResult.IsCompleted IAsyncResult.IsCompleted IAsyncResult.IsCompleted Property

定義

非同期操作が完了したかどうかを示す値を取得します。Gets a value that indicates whether the asynchronous operation has completed.

public:
 property bool IsCompleted { bool get(); };
public bool IsCompleted { get; }
member this.IsCompleted : bool
Public ReadOnly Property IsCompleted As Boolean

プロパティ値

操作が完了した場合は true。それ以外の場合は falsetrue if the operation is complete; otherwise, false.

次の例は、のIsCompletedプロパティを使用して、 IAsyncResult非同期呼び出しが完了したことを検出する方法を示しています。The following example shows how to use the IsCompleted property of the IAsyncResult to discover when an asynchronous call completes. この場合、非同期呼び出しは、デリゲートのBeginInvokeメソッドを使用して行われます。In this case, the asynchronous call is made by using the BeginInvoke method of a delegate. ユーザーインターフェイスをサービスIsCompletedするスレッドから非同期呼び出しを行う場合は、プロパティを使用して、完了をポーリングすることができます。You might use the IsCompleted property to poll for completion when making the asynchronous call from a thread that services the user interface. 完了をポーリングすると、呼び出し元スレッドは、 ThreadPool スレッドで非同期呼び出しを実行しながら、実行を継続できます。Polling for completion allows the calling thread to continue executing while the asynchronous call executes on a ThreadPool thread.

この例は、2つのクラス (非同期に呼び出されるメソッドを含むクラスと、呼び出しを行うMainメソッドを含むクラス) で構成されています。The example consists of two classes: the class that contains the method that is called asynchronously, and the class that contains the Main method that makes the call.

デリゲートを使用した非同期メソッドの呼び出しの詳細と例については、「同期メソッドの非同期呼び出し」を参照してください。For more information and more examples of calling methods asynchronously by using delegates, see Calling Synchronous Methods Asynchronously.

using namespace System;
using namespace System::Threading;
using namespace System::Runtime::InteropServices; 

namespace Examples {
namespace AdvancedProgramming {
namespace AsynchronousOperations
{
    public ref class AsyncDemo 
    {
    public:
        // The method to be executed asynchronously.
        String^ TestMethod(int callDuration, [OutAttribute] int% threadId) 
        {
            Console::WriteLine("Test method begins.");
            Thread::Sleep(callDuration);
            threadId = Thread::CurrentThread->ManagedThreadId;
            return String::Format("My call time was {0}.", callDuration);
        }
    };

    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate String^ AsyncMethodCaller(int callDuration, [OutAttribute] int% threadId);
}}}
using System;
using System.Threading; 

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncDemo 
    {
        // The method to be executed asynchronously.
        public string TestMethod(int callDuration, out int threadId) 
        {
            Console.WriteLine("Test method begins.");
            Thread.Sleep(callDuration);
            threadId = Thread.CurrentThread.ManagedThreadId;
            return String.Format("My call time was {0}.", callDuration.ToString());
        }
    }
    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate string AsyncMethodCaller(int callDuration, out int threadId);
}
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations
    Public Class AsyncDemo 
        ' The method to be executed asynchronously.
        Public Function TestMethod(ByVal callDuration As Integer, _
                <Out> ByRef threadId As Integer) As String
            Console.WriteLine("Test method begins.")
            Thread.Sleep(callDuration)
            threadId = Thread.CurrentThread.ManagedThreadId()
            return String.Format("My call time was {0}.", callDuration.ToString())
        End Function
    End Class

    ' The delegate must have the same signature as the method
    ' it will call asynchronously.
    Public Delegate Function AsyncMethodCaller(ByVal callDuration As Integer, _
        <Out> ByRef threadId As Integer) As String
End Namespace
#using <TestMethod.dll>

using namespace System;
using namespace System::Threading;
using namespace Examples::AdvancedProgramming::AsynchronousOperations;

void main() 
{
    // The asynchronous method puts the thread id here.
    int threadId;

    // Create an instance of the test class.
    AsyncDemo^ ad = gcnew AsyncDemo();

    // Create the delegate.
    AsyncMethodCaller^ caller = gcnew AsyncMethodCaller(ad, &AsyncDemo::TestMethod);
       
    // Initiate the asychronous call.
    IAsyncResult^ result = caller->BeginInvoke(3000, 
        threadId, nullptr, nullptr);

    // Poll while simulating work.
    while(result->IsCompleted == false)
    {
        Thread::Sleep(250);
        Console::Write(".");
    }

    // Call EndInvoke to retrieve the results.
    String^ returnValue = caller->EndInvoke(threadId, result);

    Console::WriteLine("\nThe call executed on thread {0}, with return value \"{1}\".",
        threadId, returnValue);
}

/* This example produces output similar to the following:

Test method begins.
.............
The call executed on thread 3, with return value "My call time was 3000.".
 */
using System;
using System.Threading;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncMain 
    {
        static void Main() {
            // The asynchronous method puts the thread id here.
            int threadId;

            // Create an instance of the test class.
            AsyncDemo ad = new AsyncDemo();

            // Create the delegate.
            AsyncMethodCaller caller = new AsyncMethodCaller(ad.TestMethod);
       
            // Initiate the asychronous call.
            IAsyncResult result = caller.BeginInvoke(3000, 
                out threadId, null, null);

            // Poll while simulating work.
            while(result.IsCompleted == false) {
                Thread.Sleep(250);
                Console.Write(".");
            }

            // Call EndInvoke to retrieve the results.
            string returnValue = caller.EndInvoke(out threadId, result);

            Console.WriteLine("\nThe call executed on thread {0}, with return value \"{1}\".",
                threadId, returnValue);
        }
    }
}

/* This example produces output similar to the following:

Test method begins.
.............
The call executed on thread 3, with return value "My call time was 3000.".
 */
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations

    Public Class AsyncMain 
        Shared Sub Main() 
            ' The asynchronous method puts the thread id here.
            Dim threadId As Integer

            ' Create an instance of the test class.
            Dim ad As New AsyncDemo()

            ' Create the delegate.
            Dim caller As New AsyncMethodCaller(AddressOf ad.TestMethod)
       
            ' Initiate the asynchronous call.
            Dim result As IAsyncResult = caller.BeginInvoke(3000, _
                threadId, Nothing, Nothing)

            ' Poll while simulating work.
            While result.IsCompleted = False
                Thread.Sleep(250)
                Console.Write(".")
            End While

            ' Call EndInvoke to retrieve the results.
            Dim returnValue As String = caller.EndInvoke(threadId, result)

            Console.WriteLine(vbCrLf & _
                "The call executed on thread {0}, with return value ""{1}"".", _
                threadId, returnValue)
        End Sub
    End Class
End Namespace

' This example produces output similar to the following:
'
'Test method begins.
'.............
'The call executed on thread 3, with return value "My call time was 3000.".

注釈

このプロパティがtrueの場合、非同期操作で使用するために割り当てたリソースを破棄しても安全であると見なすことができます。When this property is true, you can assume it is safe to discard any resources you allocate for use by the asynchronous operation.

注意 (実装者)

通常、実装者は、このプロパティの値として、プライベートフィールドまたは内部テストの値を返します。Implementers will typically return the value of a private field or internal test as the value of this property.

注意 (呼び出し元)

(同期オブジェクトで待機するのではなく) 操作の状態をポーリングするクライアントは、このプロパティを使用して操作の状態を決定します。Clients that poll for operation status (as opposed to waiting on a synchronization object) use this property to determine the status of the operation.

適用対象