Question

I have activity which needs to be active all the time. I have thread which sleep 10 sec, and monitors values taken from database, compare them and start method. I’m wondering if user go back to other applications and activities, does my activity and thread still work, or they are handled by activity manager and go to pause-stop-destroy?? How to stay them a live??
Thank you.
here is code for that thread:

 new Thread(new Runnable() {

        public void run() {
            // TODO Auto-generated method stub
            while(true){
                try {
                    Thread.sleep(10000);
                    myHendler.post(new Runnable() {

                        public void run() {
                            // TODO Auto-generated method stub

                            final Calendar cal = Calendar.getInstance();
                            int godina2 = cal.get(Calendar.YEAR);
                            int mesec2 = cal.get(Calendar.MONTH);
                            int dan2 = cal.get(Calendar.DAY_OF_MONTH);
                            int sati2 = cal.get(Calendar.HOUR_OF_DAY);
                            int minuti2 = cal.get(Calendar.MINUTE);

                            trenutniDatum = new StringBuilder().append(dan2).append("-").append(mesec2 +1).append("-").append(godina2);
                            trenutnoVreme = prepraviVreme(sati2) + ":" + prepraviVreme(minuti2);
                            for(int i = 0; i < primljenoIzBazeDatum.length; i++){
                                String bazaBroj = "";
                                String bazaText = "";
                                if(primljenoIzBazeDatum[i].toString().equals(trenutniDatum.toString()) && primljenoIzBazeVreme[i].toString().equals(trenutnoVreme)){

                                        int bazaId = Integer.parseInt(primljenoIzBazeId[i]);
                                        bazaBroj = primljenoIzBazeBroj[i].toString();
                                        bazaText = primljenoIzBazeText[i].toString();
                                        String datumPromena = "*" + primljenoIzBazeDatum[i].toString() + "* SENT *";

                                        datumVreme.open();
                                        datumVreme.updateData(bazaId, datumPromena);
                                        datumVreme.close();

                                        sendPoruka(bazaBroj, bazaText);

                                }

                            } // end for


                        } // end run
                    });
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }).start();

Answer 1

Based on my understanding of what you want to do, here is what I would do :

First, create a BroadcastReceiver

public class Poller extends BroadcastReceiver {
    private final String TAG = "Poller";
    @Override
    public void onReceive( Context context, Intent intent ) {
    Log.i(TAG, "Poller broadcastintent received");
    Intent myIntent = new Intent( context, PollerService.class );
    context.startService( myIntent );
}

then , create the service that is called and then shuts itself down

public class PollerService extends Service {
    final String TAG = "PollerService";
    @Override
    public void onStart(Intent intent, int startId) {
    Log.i(TAG, "Service onStart()");
    pollingTask.execute();
}

AsyncTask<Void, Void, Void> pollingTask = new AsyncTask<Void, Void, Void>() {
    @Override
    protected Void doInBackground(Void... param) {
        // Do what you want in the background
    }

    @Override
    protected void onPostExecute(Void result) {
        stopSelf();
    }
};
}

then, set an AlarmManager to wake the service every minute

AlarmManager am = ( AlarmManager ) getSystemService( Context.ALARM_SERVICE );
Intent alarmIntent = new Intent( "CHECK_DATABASE" );
PendingIntent pi = PendingIntent.getBroadcast(context, 0 , alarmIntent, 0 );
int type = AlarmManager.ELAPSED_REALTIME_WAKEUP;
long interval = POLLING_INTERVAL_IN_MILLISECONDS;
long triggerTime = SystemClock.elapsedRealtime() + interval;
// For short intervals setInexact repeating is same as exactRepeating, use at least fifteen minutes to make it more efficient
am.setInexactRepeating( type, triggerTime, interval, pi );
Log.i(TAG, "Set inexact alarm through AlarmManager");
}

setup the receiver in Android manifest

<receiver android:name="Poller">
    <intent-filter>
        <action android:name="CHECK_DATABASE"/>
    </intent-filter>
</receiver>

finally, unset the AlarmManager to stop polling once your required SMS is received

AlarmManager am = ( AlarmManager ) getSystemService( Context.ALARM_SERVICE );
Intent intent = new Intent( "CHECK_DATABASE" );
PendingIntent pi = PendingIntent.getBroadcast( context, 0 , intent, 0 );
am.cancel(pi);

I do think that Peter is right though and this will kill you battery unless you’ll only be checking until you get the required info and then don’t poll and that’s a short time.

Also, if you can get the exact time when you want to send the SMS with a single call from the database you can just set up the AlarmManger to wake up the service at that time, perform the action and be done with it. That would be the best approach (I can’t quite make out if that is the case from you code but it does seems to be from you comments).