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

Definición

Obtiene el valor de resultado de este objeto Task<TResult>.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

Valor de propiedad

TResult TResult TResult TResult

El valor del resultado de este Task<TResult>, que es del mismo tipo como parámetro de tipo de la tarea.The result value of this Task<TResult>, which is of the same type as the task's type parameter.

Excepciones

Se canceló la tarea.The task was canceled. La colección InnerExceptions contiene un objeto TaskCanceledException.The InnerExceptions collection contains a TaskCanceledException object.

O bien-or- Se inició una excepción durante la ejecución de la tarea.An exception was thrown during the execution of the task. La colección InnerExceptions contiene información sobre la excepción o excepciones.The InnerExceptions collection contains information about the exception or exceptions.

Ejemplos

El ejemplo siguiente es una utilidad de línea de comandos que calcula el número de bytes en los archivos en cada directorio cuyo nombre se pasa como un argumento de línea de comandos.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. Si el directorio contiene archivos, ejecuta una expresión lambda que crea una instancia de un FileStream objeto para cada archivo en el directorio y recupera el valor de su FileStream.Length propiedad.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. Si un directorio no contiene ningún archivo, simplemente llama a la FromResult método para crear una tarea cuya Task<TResult>.Result propiedad es cero (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). Al finalizan las tareas, el número total de bytes en archivos de todo un directorio está disponible en el Result propiedad.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

Comentarios

Obtener acceso a descriptor de acceso de la propiedad get bloquea el subproceso que realiza la llamada hasta que la operación asincrónica se complete; equivale a llamar a la Wait método.Accessing the property's get accessor blocks the calling thread until the asynchronous operation is complete; it is equivalent to calling the Wait method.

Una vez que el resultado de una operación está disponible, se almacena y se devuelve inmediatamente en las llamadas posteriores a la Result propiedad.Once the result of an operation is available, it is stored and is returned immediately on subsequent calls to the Result property. Tenga en cuenta que, si se produjo una excepción durante la operación de la tarea, o si se canceló la tarea, el Result propiedad no devuelve un valor.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. En su lugar, al intentar tener acceso a la propiedad valor produce un AggregateException excepción.Instead, attempting to access the property value throws an AggregateException exception.

Se aplica a

Consulte también: