Task<TResult>.Result 屬性


取得這個 Task<TResult> 的結果值。Gets the result value of this Task<TResult>.

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



這個的結果值,與工作的 Task<TResult> 類型參數屬於相同的類型。The result value of this Task<TResult>, which is of the same type as the task's type parameter.


工作已取消。The task was canceled. InnerExceptions 集合包含 TaskCanceledException 物件。The InnerExceptions collection contains a TaskCanceledException object.

-或--or- 在工作執行期間擲回例外狀況。An exception was thrown during the execution of the task. InnerExceptions 集合包含例外狀況的相關資訊。The InnerExceptions collection contains information about the exception or exceptions.


下列範例是命令列公用程式,會計算每個目錄中檔案的位元組數目,其名稱會以命令列引數的形式傳遞。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. 如果目錄包含檔案,則會執行 lambda 運算式,將目錄中每個檔案的物件具現化, FileStream 並抓取其 FileStream.Length 屬性值。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. 如果目錄不包含任何檔案,則只會呼叫 FromResult 方法來建立其 Task<TResult>.Result 屬性為零的工作 (0) 。If a directory contains no files, it simply calls the FromResult method to create a task whose Task<TResult>.Result property is zero (0). 當工作完成時,所有目錄檔案中的總位元組數可從 Result 屬性取得。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++)

         try {
         // 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]);
               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);
            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
         ' 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))
               Console.WriteLine("{0:N0} bytes in files in '{1}'",
                                 tasks(ctr).Result, args(ctr + 1))
            End If
         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."))
         Dim files As String() = Directory.GetFiles(filePath)
         If files.Length = 0 Then
            Return Task.FromResult(0L)
            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)
                                                        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


存取屬性的 get 存取子會封鎖呼叫執行緒,直到非同步作業完成為止;這相當於呼叫 Wait 方法。Accessing the property's get accessor blocks the calling thread until the asynchronous operation is complete; it is equivalent to calling the Wait method.

一旦作業的結果可供使用,就會儲存,並在後續呼叫屬性時立即傳回 ResultOnce the result of an operation is available, it is stored and is returned immediately on subsequent calls to the Result property. 請注意,如果在工作的作業期間發生例外狀況,或工作已取消,則屬性不會傳回 Result 值。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. 相反地,嘗試存取屬性值會擲回 AggregateException 例外狀況。Instead, attempting to access the property value throws an AggregateException exception.