CODEWITHSUNDEEP
androidandroid-asynctaskprogressdialog
SleepyBear
SleepyBear

Reputation: 53

ProgressDialog in AsyncTask onPreExecute, but it appears after doInBackground

This is part of my application. (You can run code below as an isolated application) On that website (url), using php language, parse some numbers from other website, and make an array and encode it to JSON array, and show.

But, with the code below (without dismiss function!) ProgressDialog appears after doInBackground.

When I add dismiss function to onPostExecute like below, it never appears. But When I set log for checking dialog window, it says that there was an dialog.

I heard that doInBackground freezes UI, but it freezes before dialog is shown.

Other similar questions have found solution, erasing .get() from mAsyncTask().execute().get(), but I don't have any get() in my code.

Boolean variable loadfinish is for waiting finishing asynctask, to show results from that website after asynctask. If I delete while(loadFinish == false) there, it automacally appears and disappears very well, but I can't show result immediately...

Add) I found that it takes several seconds to dialog appear after doInBackground... why?!

Add2) I've tried to move dialog codes before and after new mAsyncTask().execute(), but it doesn't work too...

public class MainActivity extends Activity {

boolean loadFinish;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button start = (Button) findViewById(R.id.start); 
//just a button for starting asynctask
    start.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            loadFinish = false;
            new mAsyncTask().execute(); 
// get and make json array to java array
            while (loadFinish == false)
                ;
        }
    });
// add array to Custom_List_Data, and set custom row_adapter to listView. 
// if I delete while(loadFinish == false), array with initial data is added.
}

private class mAsyncTask extends AsyncTask<String, String, String> {

    ProgressDialog dialog;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        dialog = new ProgressDialog(MainActivity.this);
        dialog.setMessage("asdf");
        dialog.setIndeterminate(true);
        dialog.setCancelable(false);
        dialog.show();
    }

    @Override
    protected String doInBackground(String... params) {

        String url = "http://songdosiyak.url.ph/MouiRate/etoos/3/main/";
        String response_str = "";

        HttpClient client = new DefaultHttpClient();
        HttpGet request = new HttpGet(url);
        ResponseHandler<String> responseHandler = new BasicResponseHandler();

        try {
            response_str = client.execute(request, responseHandler);
        } catch (ClientProtocolException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }

        loadFinish = true;
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
                    dialog.dismiss();
    }
}

}

Sorry for my poor English language skill and thank you for reading!

Upvotes: 1

Views: 1083

Answers (3)

iluu
iluu

Reputation: 406

As Gabe mentioned you don't need the loop, all you need is some more understanding what the async methods should do.

You introduced the result, because you want to display the result. All you have to do is to return your response_str in doInBackground. It will be then available to you as a param to onPostExecute where you can easily display it, or do whatever you need to do with it.

So to summarize:

  • Remove the loop
  • Return value response_str or whatever from doInBackground
  • Display value in onPostExecute
  • And remove loadFinish variable as its not needed at all

Hope that helps.

Upvotes: 1

Jonny07
Jonny07

Reputation: 625

It may be worth looking into using an async library.

Using a library to help handle async callbacks can be super helpful for this as you can start the spinner, call your api, then stop the spinner in either the onSuccess function, or your success callback method in your class.

This is the one I usually use:

LoopJ's Async HTTP Callback Library

This will handle GET and POST requests with a lot of cool features such as custom timeouts, JSON format, onSuccess() and onFailure() methods, etc. There's a lot of working examples of this library too. I've used it in all my apps and haven't had any problems yet!

Hopefully this helps.

Upvotes: 0

Gabe Sechan
Gabe Sechan

Reputation: 93561

Because you're using an AsyncTask totally wrong. You're busy looping waiting for it to finish. NEVER do that- if you're doing that there's no point in using an AsyncTask. At any rate, the reason it won't appear is that the UI doesn't update until the UI thread returns to the event loop inside the Android Framework and runs the drawing code, which happens after onClick returns. So you won't draw until your busy loop exits, which happens after doInBackground finishes.

The solution is to remove the loop waiting for the AsyncTask to finish in your onClick. If you have logic that needs to run after it, put it in onPostExecute.

Upvotes: 0

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