StringReader.ReadLineAsync Método

Definição

Lê uma linha de caracteres assincronamente da cadeia de caracteres atual e retorna os dados como uma cadeia de caracteres.Reads a line of characters asynchronously from the current string and returns the data as a string.

public:
 override System::Threading::Tasks::Task<System::String ^> ^ ReadLineAsync();
public override System.Threading.Tasks.Task<string> ReadLineAsync ();
public override System.Threading.Tasks.Task<string?> ReadLineAsync ();
[System.Runtime.InteropServices.ComVisible(false)]
public override System.Threading.Tasks.Task<string> ReadLineAsync ();
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
[<System.Runtime.InteropServices.ComVisible(false)>]
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
Public Overrides Function ReadLineAsync () As Task(Of String)

Retornos

Task<String>

Uma tarefa que representa a operação de leitura assíncrona.A task that represents the asynchronous read operation. O valor do parâmetro TResult contém a próxima linha do leitor de cadeia de caracteres ou null se todos os caracteres tiverem sido lidos.The value of the TResult parameter contains the next line from the string reader, or is null if all the characters have been read.

Atributos

Exceções

O número de caracteres na próxima linha é maior que MaxValue.The number of characters in the next line is larger than MaxValue.

O leitor de cadeia de caracteres foi descartado.The string reader has been disposed.

O leitor está sendo usado no momento por uma operação de leitura anterior.The reader is currently in use by a previous read operation.

Exemplos

O exemplo a seguir mostra como ler uma linha por vez de uma cadeia de caracteres de forma assíncrona.The following example shows how to read one line at a time from a string asynchronously.

using System;
using System.IO;
using System.Text;

namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            ReadCharacters();
        }

        static async void ReadCharacters()
        {
            StringBuilder stringToRead = new StringBuilder();
            stringToRead.AppendLine("Characters in 1st line to read");
            stringToRead.AppendLine("and 2nd line");
            stringToRead.AppendLine("and the end");

            string readText;

            using (StringReader reader = new StringReader(stringToRead.ToString()))
            {
                while ((readText = await reader.ReadLineAsync()) != null)
                {
                    Console.WriteLine(readText);
                }
            }
        }
    }
}
// The example displays the following output:
//
// Characters in 1st line to read
// and 2nd line
// and the end
//
Imports System.IO
Imports System.Text

Module Module1

    Sub Main()
        ReadCharacters()
    End Sub

    Async Sub ReadCharacters()
        Dim stringToRead = New StringBuilder()
        stringToRead.AppendLine("Characters in 1st line to read")
        stringToRead.AppendLine("and 2nd line")
        stringToRead.AppendLine("and the end")

        Using reader As StringReader = New StringReader(stringToRead.ToString())
            Dim readText As String = Await reader.ReadLineAsync()
            While Not IsNothing(readText)
                Console.WriteLine(readText)
                readText = Await reader.ReadLineAsync()
            End While
        End Using
    End Sub
End Module
' The example displays the following output:
'
' Characters in 1st line to read
' and 2nd line
' and the end
'

Aplica-se a