WindowsRuntimeStorageExtensions.OpenStreamForWriteAsync Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Overloads
| OpenStreamForWriteAsync(IStorageFile) |
Retrieves a stream for writing to a specified file. |
| OpenStreamForWriteAsync(IStorageFolder, String, CreationCollisionOption) |
Retrieves a stream for writing to a file in the specified parent folder. |
OpenStreamForWriteAsync(IStorageFile)
Important
This API is not CLS-compliant.
Retrieves a stream for writing to a specified file.
public:
[System::Runtime::CompilerServices::Extension]
static System::Threading::Tasks::Task<System::IO::Stream ^> ^ OpenStreamForWriteAsync(Windows::Storage::IStorageFile ^ windowsRuntimeFile);[System.CLSCompliant(false)]
public static System.Threading.Tasks.Task<System.IO.Stream> OpenStreamForWriteAsync (this Windows.Storage.IStorageFile windowsRuntimeFile);[<System.CLSCompliant(false)>]
static member OpenStreamForWriteAsync : Windows.Storage.IStorageFile -> System.Threading.Tasks.Task<System.IO.Stream><Extension()>
Public Function OpenStreamForWriteAsync (windowsRuntimeFile As IStorageFile) As Task(Of Stream)Parameters
- windowsRuntimeFile
- IStorageFile
The Windows Runtime IStorageFile object to write to.
Returns
A task that represents the asynchronous write operation.
- Attributes
Exceptions
windowsRuntimeFile is null.
The file could not be opened or retrieved as a stream.
Examples
The following example shows how to open a file as a Stream in a Windows Store app, and write to it by using an instance of the StreamReader class.
using System;
using System.IO;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
namespace ExampleApplication
{
public sealed partial class BlankPage : Page
{
public BlankPage()
{
this.InitializeComponent();
}
private async void CreateButton_Click(object sender, RoutedEventArgs e)
{
StorageFile newFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("testfile3.txt");
using (StreamWriter writer = new StreamWriter(await newFile.OpenStreamForWriteAsync()))
{
await writer.WriteLineAsync("new entry");
await writer.WriteLineAsync(UserText.Text);
}
}
private async void VerifyButton_Click(object sender, RoutedEventArgs e)
{
StorageFile openedFile = await ApplicationData.Current.LocalFolder.GetFileAsync("testfile3.txt");
using (StreamReader reader = new StreamReader(await openedFile.OpenStreamForReadAsync()))
{
Results.Text = await reader.ReadToEndAsync();
}
}
}
}
Imports System.IO
Imports Windows.Storage
NotInheritable Public Class BlankPage
Inherits Page
Private Async Sub CreateButton_Click(sender As Object, e As RoutedEventArgs)
Dim newFile As StorageFile = Await ApplicationData.Current.LocalFolder.CreateFileAsync("testfile4.txt")
Using writer As StreamWriter = New StreamWriter(Await newFile.OpenStreamForWriteAsync())
Await writer.WriteLineAsync("new entry")
Await writer.WriteLineAsync(UserText.Text)
End Using
End Sub
Private Async Sub VerifyButton_Click(sender As Object, e As RoutedEventArgs)
Dim openedFile As StorageFile = Await ApplicationData.Current.LocalFolder.GetFileAsync("testfile4.txt")
Using reader As StreamReader = New StreamReader(Await openedFile.OpenStreamForReadAsync())
Results.Text = Await reader.ReadToEndAsync()
End Using
End Sub
End Class
The next example shows the XAML code that is associated with the previous example.
<Page
x:Class="ExampleApplication.BlankPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:ExampleApplication"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<StackPanel Background="{StaticResource ApplicationPageBackgroundBrush}" VerticalAlignment="Center" HorizontalAlignment="Center">
<TextBlock Text="Provide text to write to file:"></TextBlock>
<TextBox Name="UserText" Width="400"></TextBox>
<Button Name="CreateButton" Content="Create File" Click="CreateButton_Click"></Button>
<Button Name="VerifyButton" Content="Verify Contents" Click="VerifyButton_Click"></Button>
<TextBlock Name="Results"></TextBlock>
</StackPanel>
</Page>
Remarks
Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IStorageFile. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Applies to
OpenStreamForWriteAsync(IStorageFolder, String, CreationCollisionOption)
Important
This API is not CLS-compliant.
Retrieves a stream for writing to a file in the specified parent folder.
public:
[System::Runtime::CompilerServices::Extension]
static System::Threading::Tasks::Task<System::IO::Stream ^> ^ OpenStreamForWriteAsync(Windows::Storage::IStorageFolder ^ rootDirectory, System::String ^ relativePath, Windows::Storage::CreationCollisionOption creationCollisionOption);[System.CLSCompliant(false)]
public static System.Threading.Tasks.Task<System.IO.Stream> OpenStreamForWriteAsync (this Windows.Storage.IStorageFolder rootDirectory, string relativePath, Windows.Storage.CreationCollisionOption creationCollisionOption);[<System.CLSCompliant(false)>]
static member OpenStreamForWriteAsync : Windows.Storage.IStorageFolder * string * Windows.Storage.CreationCollisionOption -> System.Threading.Tasks.Task<System.IO.Stream><Extension()>
Public Function OpenStreamForWriteAsync (rootDirectory As IStorageFolder, relativePath As String, creationCollisionOption As CreationCollisionOption) As Task(Of Stream)Parameters
- rootDirectory
- IStorageFolder
The Windows Runtime IStorageFile object that contains the file to write to.
- relativePath
- String
The path, relative to the root folder, to the file to write to.
- creationCollisionOption
- CreationCollisionOption
The Windows Runtime CreationCollisionOption enumeration value that specifies the behavior to use when the name of the file to create is the same as the name of an existing file.
Returns
A task that represents the asynchronous write operation.
- Attributes
Exceptions
rootDirectory or relativePath is null.
relativePath is empty or contains only white-space characters.
The file could not be opened or retrieved as a stream.
Examples
The following example shows how to open a file as a Stream in a Windows Store app, and write to it by using an instance of the StreamReader class.
using System;
using System.IO;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
namespace ExampleApplication
{
public sealed partial class BlankPage : Page
{
public BlankPage()
{
this.InitializeComponent();
}
private async void CreateButton_Click(object sender, RoutedEventArgs e)
{
using (StreamWriter writer =
new StreamWriter(await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(
"testfile.txt", CreationCollisionOption.OpenIfExists)))
{
await writer.WriteLineAsync("new entry");
await writer.WriteLineAsync(UserText.Text);
}
}
private async void VerifyButton_Click(object sender, RoutedEventArgs e)
{
StorageFile openedFile = await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt");
using (StreamReader reader = new StreamReader(await openedFile.OpenStreamForReadAsync()))
{
Results.Text = await reader.ReadToEndAsync();
}
}
}
}
Imports System.IO
Imports Windows.Storage
NotInheritable Public Class BlankPage
Inherits Page
Private Async Sub CreateButton_Click(sender As Object, e As RoutedEventArgs)
Using writer As StreamWriter =
New StreamWriter(Await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(
"testfile.txt", CreationCollisionOption.OpenIfExists))
Await writer.WriteLineAsync("new entry")
Await writer.WriteLineAsync(UserText.Text)
End Using
End Sub
Private Async Sub VerifyButton_Click(sender As Object, e As RoutedEventArgs)
Dim openedFile As StorageFile = Await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt")
Using reader As StreamReader = New StreamReader(Await openedFile.OpenStreamForReadAsync())
Results.Text = Await reader.ReadToEndAsync()
End Using
End Sub
End Class
The next example shows the XAML code that is associated with the previous example.
<Page
x:Class="ExampleApplication.BlankPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:ExampleApplication"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<StackPanel Background="{StaticResource ApplicationPageBackgroundBrush}" VerticalAlignment="Center" HorizontalAlignment="Center">
<TextBlock Text="Provide text to write to file:"></TextBlock>
<TextBox Name="UserText" Width="400"></TextBox>
<Button Name="CreateButton" Content="Create File" Click="CreateButton_Click"></Button>
<Button Name="VerifyButton" Content="Verify Contents" Click="VerifyButton_Click"></Button>
<TextBlock Name="Results"></TextBlock>
</StackPanel>
</Page>
Remarks
Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IStorageFolder. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
