Need help with AsyncTasks - Android Application

Hey, I have an application which logs onto a few sites using defaulthttpclient and I've found I'm going to need to use the AsyncTask as the requests hold up the UI thread. In my code, I create an instance of a state class i.e. State state = new O2State(); with different states for different sites.

I then call state.logon(String username, String password); which returns a string containing details of the result so:

String result = state.logon(username, password);

I've been trying to implement asynctasks to run this code in another thread and return the string back to the UI thread on completion. The idea is I will display a progress dialog, run the thread, and on complete, will display a dialog 开发者_运维问答with the result.

I've been looking at this example:

public void onClick(View v) {
new DownloadImageTask().execute("http://example.com/image.png");
}

private class DownloadImageTask extends AsyncTask {
     protected Bitmap doInBackground(String... urls) {
         return loadImageFromNetwork(urls[0]);
     }

     protected void onPostExecute(Bitmap result) {
         mImageView.setImageBitmap(result);
     }
 }

Where I'm stuck is: I don't think I'll need any arguments, but doinbackground seems to require a list of parameters. I'm also unfamiliar with this time of method argument declaration.

Secondly: I'm not sure how to return the resulting string when the thread is finished executing. Should I just create a "DoThisWhenTheThreadIsFinished(String result)" and call this from onPostExecute?

Anyway, I hope this isn't too confusing to read and I'd really appreciate any help you can offer. Thanks

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Where you don't need parameters just specify the type (e.g. String) and ignore it, or you could use the Void class (note the capital V).

What you suggest for how to return control back to the UI thread to reflect the update is a good approach. i.e. in onPostExecute() call a method on the activity to update the UI.

As a general rule if any operations will take more than a couple of hundred milliseconds, use a separate thread. You may also want to use a rotating progress indicator to show the app is doing something.

(when people answer your questions, always rate the ones you like, and pick one as the "best" answer. you get points doing this, and it helps others later).