Question

I wrote a program for downloading an image from web using AsyncTask in service. The downloading process works normally. I am using a notification for indicating the download progress, I also have two buttons for start downloading and stop downloading.
But when I click the stop button the ongoing download can’t stop. The notification manager continue the same.

Main activity:

public class ServicedownloadActivity extends Activity implements
        OnClickListener {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        b1 = (Button) findViewById(R.id.button1);
        b2 = (Button) findViewById(R.id.button2);
        b1.setOnClickListener(this);
        b2.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        if (v.getId() == R.id.button1) {
            Intent intent = new Intent(ServicedownloadActivity.this,
                    Myclass.class);
            startService(intent);

        }
        if (v.getId() == R.id.button2) {

            Intent intent = new Intent(ServicedownloadActivity.this,
                    Myclass.class);
            stopService(intent);
        }
    }
}

---

Class contains serivce and asynchTask

public class Myclass extends Service {

    URLConnection connection;
    private final Random mGenerator = new Random();

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    public int getRandomNumber() {
        return mGenerator.nextInt(100);
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d("df", "From oncreate");
        Toast.makeText(this, "on create", Toast.LENGTH_SHORT).show();

    }
    class DownloadWebPageTask extends AsyncTask<String, String, String> {
        String responseTextt;
        NotificationManager notificationManager;
        Notification notification;
        CharSequence contentText;
        Context context;
        CharSequence contentTitle;
        PendingIntent contentIntent;
        int HELLO_ID = 1;
        long time;
        int icon;
        CharSequence tickerText;

        public void downloadNotification() {
            String ns = Context.NOTIFICATION_SERVICE;
            notificationManager = (NotificationManager) getSystemService(ns);
            icon = R.drawable.ic_launcher;
            tickerText = "Downloading...";
            time = System.currentTimeMillis();
            notification = new Notification(icon, tickerText, time);
            context = getApplicationContext();
            contentTitle = "Your download is in progress";
            contentText = "0% complete";
            Intent notificationIntent = new Intent(Intent.ACTION_VIEW);
            notificationIntent.setType("audio/*");
            contentIntent = PendingIntent.getActivity(context, 0,
                    notificationIntent, 0);
            notification.setLatestEventInfo(context, contentTitle,
                    contentText, contentIntent);
            notificationManager.notify(HELLO_ID, notification);

        }

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

            try {

                Log.d("trys:", "try");
                URL url = new URL(
                        "http://www.zapiture.com/resources/IMG_6812.JPG");
                connection = url.openConnection();
                connection.connect();
                int fileLength = connection.getContentLength();
                InputStream input = new BufferedInputStream(url
                        .openStream());
                OutputStream output = new FileOutputStream(Environment
                        .getExternalStorageDirectory()
                        + "/img23.jpg");

                byte data[] = new byte[1024];
                long total = 0;
                int count;
                int previousProgress = 0;
                while ((count = input.read(data)) != -1) {
                    total += count;
                    if ((int) (total * 100 / fileLength) > previousProgress) {
                        previousProgress = (int) (total * 100 / fileLength);
                        publishProgress(""
                                + (int) (total * 100 / fileLength));
                        output.write(data, 0, count);
                    }
                }

                output.flush();
                output.close();
                input.close();

            } catch (Exception e) {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPreExecute() {
            downloadNotification();

            super.onPreExecute();
            ;
        }

        @Override
        public void onProgressUpdate(String... progress) {

            contentText = Integer.parseInt(progress[0]) + "% complete";
            notification.setLatestEventInfo(context, contentTitle,
                    contentText, contentIntent);
            notificationManager.notify(HELLO_ID, notification);
            super.onProgressUpdate(progress);
        }
    }

    @Override
    public void onStart(Intent intent, int startId) {
        // TODO Auto-generated method stub
        super.onStart(intent, startId);
        Log.d("sf", "On Start");
        Toast.makeText(this, "on start", Toast.LENGTH_SHORT).show();
        DownloadWebPageTask task = new DownloadWebPageTask();

        task.execute();
    }

    @Override
    public void onDestroy() {
        stopSelf();
        super.onDestroy();
        Log.d("df", "From on Destroy");
        Toast.makeText(this, "on destroy", Toast.LENGTH_SHORT).show();
    }
}

Answer 1

I would suggest you that Make a Boolean flag variable initially true and while in onDestroy() change it to false

Now in doInBackground check the variable status if true then continue your task if false then stop it and just call return;

As the AsyncTask run in their separate process so evenif the Activity/Service got destroyed they keep executting.