How to implement a ProgressDialog while Activity requests a SoapObject from a Web Service?

Question

I know that ProgressDialog with Threads questions have been asked many times but none of the solutions seem to work for my project. Basically what I want to do is this: 1) when

Answer 1

If you really want to use a Thread instead of an AsyncTask you can try it this way:

public class XXX extends Activity implements OnClickListener {
...
    private static int HANDLER_MESSAGE_AUTH_REQUEST_COMPLETE = 10;
...
    private void performAuthentication(){
        authProgressDialog = ProgressDialog.show(XXX.this, "", "Authenticating...", true, false);
        Thread backgroundThread = new Thread() {
            @Override
            public void run() {
                authenticate();
            }
        }
        backgroundThread.start();
    }

    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch(msg.what){
            case HANDLER_MESSAGE_AUTH_REQUEST_COMPLETE:
                authProgressDialog.dismiss();
                break;
            }
        }
    }

    private void authenticate(){
        // existing authenticate code goes here
        ...
        Message msg = Message.obtain();
        msg.what = HANDLER_MESSAGE_AUTH_REQUEST_COMPLETE;
        handler.sendMessage(msg);
        // existing authenticateReal code goes here
        ...
    }
}

From your code it is not 100% clear where the variable mHandler is assigned to the new Handler(). To be clear, in my code this should be a private field on the class itself. You will also need some error handling in your authenticate() method to send a message to dismiss the dialog if you encounter an error.

Answer 2

For your last problem, put "Looper.prepare();" into your run() method.

        @Override
        public void run() {
            Looper.prepare();
            authenticate(); // method that calls the API via SOAP
            authenticateReal(); // method that handles the response
        }

Did you check if your response in your authenticate() method is working correctly? (using LogCat to display the response)

Otherwise, better use AsyncTask (like suggested).

Answer 3

You better use AsyncTask (which is the Android way):

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    new TheTask().execute();
}

private class TheTask extends AsyncTask<Void, Void, Void>{

    @Override
    protected void onPreExecute() {
        authProgressDialog = ProgressDialog.show(XXX.this, "", "Authenticating...", true, false);
    }

    @Override
    protected Void doInBackground(Void... params) {
        authenticate(); // method that calls the API via SOAP
        authenticateReal(); // method that handles the response
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        authProgressDialog.dismiss();
    }
}

By the way... I have found this presentation to be very useful (it talks about REST apps, but you can apply the same concept for different kind of apps): Developing Android REST client applications

Answer 4

As others already wrote, AsyncTask is the way to proceed.

BUT: AsyncTask and Threads have some pitfalls for UI elements:

If you change the phone orientation and did not set android:configChanges="keyboardHidden|orientation" for your Activity (means you have to handle onConfigChange by yourself) in the Manifest.xml, an orientation change will destroy and recreate your Activity and ContentView and also disconnect the ProgressDialog from the visible window (it's connected to the old one). Android is NOT going to kill your Thread or AsyncTask. It also won't kill it if the Activity is destroyed. Those background Task continue until they are done.

Trying to dismiss() your previsously created ProgressDialog throws an exception after the ContentView got destroyed, as it is not part of your window anymore. try/catch a LOT in situations doing something detached (async) work. Everything you possibly rely on just could have vanished or replaced by something different when onPostExecute() gets called again. Eventually think about registering every ASyncTask you start in some Array in your Activity and try to cancel() them at your Activity.onDestroy().