CODEWITHSUNDEEP
c#androidmultithreadingxamarin
Rick
Rick

Reputation: 927

Xamarin: Update UI from long running native process

I'm writing a Xamarin Android app and I have a long running native (Java) process. I want to capture the output of the process (stdout, stderr) and update the UI with the progress. The code I have below doesn't work. Right now it blocks the UI thread.

What is the right way to update the UI without blocking the UI thread?

string[] myCmd = { "unix_cmd", "--args" };

process = Runtime.GetRuntime().Exec(myCmd);
BufferedReader bufferedStdoutReader = new BufferedReader(new InputStreamReader(process.InputStream));
BufferedReader bufferedStderrReader = new BufferedReader(new InputStreamReader(process.ErrorStream));

logView.Text += "Stdout >>>>>>>>" + System.Environment.NewLine;
var txt="";
txt = bufferedStdoutReader.ReadLine();
while (txt != null)
{
    logView.Text += txt + System.Environment.NewLine;
    txt = bufferedStdoutReader.ReadLine();
}
logView.Text += "Stdout <<<<<<<<<" + System.Environment.NewLine + System.Environment.NewLine;

logView.Text += "Stderr >>>>>>>>>>" + System.Environment.NewLine;
txt = bufferedStderrReader.ReadLine();
while (txt != null)
{
    logView.Text += txt + System.Environment.NewLine;
    txt = bufferedStderrReader.ReadLine();
}
logView.Text += "Stderr <<<<<<<<<<" + System.Environment.NewLine;

process.WaitFor();

Upvotes: 0

Views: 280

Answers (1)

Grace Feng
Grace Feng

Reputation: 16652

I want to capture the output of the process (stdout, stderr) and update the UI with the progress.

I think you can try to wrap your code for capturing the output of the process into a task for example:

public Task<CapturOutputResult> CapturOutput(string) {
    return Task.Run(delegate {
        ...
        return result;
    });
}

and then execute the task like this:

var result = await CapturOutput(string);

and finally update your UI in UI thread for example:

Application.SynchronizationContext.Post(_ => {/* invoked on UI thread */}, null);

Upvotes: 1

Related Questions