Task<TResult>.Result Task<TResult>.Result Task<TResult>.Result Task<TResult>.Result Property

定義

この Task<TResult> の結果値を取得します。Gets the result value of this Task<TResult>.

public:
 property TResult Result { TResult get(); };
public TResult Result { get; }
member this.Result : 'Result
Public ReadOnly Property Result As TResult

プロパティ値

TResult TResult TResult TResult

このTask<TResult>の結果値。タスクの型パラメーターと同じ型になります。The result value of this Task<TResult>, which is of the same type as the task's type parameter.

例外

タスクが取り消されました。The task was canceled. InnerExceptions コレクションに TaskCanceledException オブジェクトが含まれています。The InnerExceptions collection contains a TaskCanceledException object.

- または --or- タスクの実行時に例外がスローされました。An exception was thrown during the execution of the task. InnerExceptions コレクションには、例外に関する情報が含まれています。The InnerExceptions collection contains information about the exception or exceptions.

次の例は、コマンドライン引数として渡された名前を持つ各ディレクトリ内のファイルのバイト数を計算するコマンドラインユーティリティです。The following example is a command-line utility that calculates the number of bytes in the files in each directory whose name is passed as a command-line argument. ディレクトリにファイルが含まれている場合は、ディレクトリ内のFileStream各ファイルのオブジェクトをインスタンス化し、そのFileStream.Lengthプロパティの値を取得するラムダ式を実行します。If the directory contains files, it executes a lambda expression that instantiates a FileStream object for each file in the directory and retrieves the value of its FileStream.Length property. ディレクトリにファイルが含まれていない場合はFromResult 、メソッドを呼び出して、 Task<TResult>.Resultプロパティがゼロ (0) のタスクを作成するだけです。If a directory contains no files, it simply calls the FromResult method to create a task whose Task<TResult>.Result property is zero (0). タスクが完了すると、すべてのディレクトリのファイルの合計バイト数をResultプロパティから取得できるようになります。When the tasks finish, the total number of bytes in all a directory's files is available from the Result property.

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      string[] args = Environment.GetCommandLineArgs();
      if (args.Length > 1) {
         List<Task<long>> tasks = new List<Task<long>>();
         for (int ctr = 1; ctr < args.Length; ctr++)
            tasks.Add(GetFileLengthsAsync(args[ctr]));

         try {
            Task.WaitAll(tasks.ToArray());
         }
         // Ignore exceptions here.
         catch (AggregateException) {}

         for (int ctr = 0 ; ctr < tasks.Count; ctr++) {
            if (tasks[ctr].Status == TaskStatus.Faulted)
               Console.WriteLine("{0} does not exist", args[ctr + 1]);
            else
               Console.WriteLine("{0:N0} bytes in files in '{1}'",
                                 tasks[ctr].Result, args[ctr + 1]);
         }
      }
      else {
         Console.WriteLine("Syntax error: Include one or more file paths.");
      }
   }

   private static Task<long> GetFileLengthsAsync(string filePath)
   {
      if (! Directory.Exists(filePath)) {
         return Task.FromException<long>(
                     new DirectoryNotFoundException("Invalid directory name."));
      }
      else {
         string[] files = Directory.GetFiles(filePath);
         if (files.Length == 0)
            return Task.FromResult(0L);
         else
            return Task.Run( () => { long total = 0;
                                     Parallel.ForEach(files, (fileName) => {
                                                 var fs = new FileStream(fileName, FileMode.Open,
                                                                         FileAccess.Read, FileShare.ReadWrite,
                                                                         256, true);
                                                 long length = fs.Length;
                                                 Interlocked.Add(ref total, length);
                                                 fs.Close(); } );
                                     return total;
                                   } );
      }
   }
}
// When launched with the following command line arguments:
//      subdir . newsubdir
// the example displays output like the following:
//       0 bytes in files in 'subdir'
//       2,059 bytes in files in '.'
//       newsubdir does not exist
Imports System.Collections.Generic
Imports System.IO
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim args() As String = Environment.GetCommandLineArgs()
      If args.Length > 1 Then
         Dim tasks As New List(Of Task(Of Long))
         For ctr = 1 To args.Length - 1
            tasks.Add(GetFileLengthsAsync(args(ctr)))
         Next
         Try
            Task.WaitAll(tasks.ToArray())
         ' Ignore exceptions here.
         Catch e As AggregateException
         End Try

         For ctr As Integer = 0 To tasks.Count - 1
            If tasks(ctr).Status = TaskStatus.Faulted Then
               Console.WriteLine("{0} does not exist", args(ctr + 1))
            Else
               Console.WriteLine("{0:N0} bytes in files in '{1}'",
                                 tasks(ctr).Result, args(ctr + 1))
            End If
         Next
      Else
         Console.WriteLine("Syntax error: Include one or more file paths.")
      End If
   End Sub
   
   Private Function GetFileLengthsAsync(filePath As String) As Task(Of Long)
      If Not Directory.Exists(filePath) Then
         Return Task.FromException(Of Long)(
                     New DirectoryNotFoundException("Invalid directory name."))
      Else
         Dim files As String() = Directory.GetFiles(filePath)
         If files.Length = 0 Then
            Return Task.FromResult(0L)
         Else
            Return Task.Run( Function()
                                Dim total As Long = 0
                                Dim lockObj As New Object
                                Parallel.ForEach(files, Sub(fileName)
                                                           Dim fs As New FileStream(fileName, FileMode.Open,
                                                                     FileAccess.Read, FileShare.ReadWrite,
                                                                     256, True)
                                                           Dim length As Long = fs.Length
                                                           Interlocked.Add(total, length)
                                                           fs.Close()
                                                        End Sub)
                                Return total
                             End Function )
         End If
      End If
   End Function
End Module
' When launched with the following command line arguments:
'      subdir . newsubdir
' the example displays output like the following:
'       0 bytes in files in 'subdir'
'       2,059 bytes in files in '.'
'       newsubdir does not exist

注釈

プロパティの get アクセサーにアクセスすると、非同期操作が完了するまで呼び出し元のスレッドがブロックされます。これは、 Waitメソッドを呼び出すことと同じです。Accessing the property's get accessor blocks the calling thread until the asynchronous operation is complete; it is equivalent to calling the Wait method.

操作の結果が使用可能になると、その結果は格納され、その後のプロパティResultの呼び出し時に直ちに返されます。Once the result of an operation is available, it is stored and is returned immediately on subsequent calls to the Result property. タスクの操作中に例外が発生した場合、またはタスクがキャンセルResultされた場合、プロパティは値を返しません。Note that, if an exception occurred during the operation of the task, or if the task has been cancelled, the Result property does not return a value. 代わりに、プロパティ値にアクセスしようとするとAggregateException 、例外がスローされます。Instead, attempting to access the property value throws an AggregateException exception.

適用対象

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