How to show progress in prefrence activity pending intent

I want to do a tas开发者_开发百科k in certain interval automatically.I called the service in pending intent as below

             alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
    mAlarmSender = PendingIntent.getService(Schedule.this, 0, new    Intent(Schedule.this,
                                        Schedule_service.class), 0);
                        new Thread(new Runnable() {
                            public void run() {
                                Schedule.this.finish();
                                alarmManager.setRepeating(
                                        AlarmManager.RTC_WAKEUP, SysTime,
                                        interval, mAlarmSender);
                                state = true;
                            }
                        }).start();

But there is a blank screen while the service runs and force closes when I press back button.So I tried it in async task also to show progress until the service finish but it also doesnt help.Any solution or guidance please, Thanks.

Intent intent = new Intent(context, reminderService.class);
        PendingIntent pendingIntent = PendingIntent.getService(context, 1, intent, 0);
        AlarmManager alarmmanager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);

        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);

        alarmmanager.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), 1000 * 60 * 60 * 24, pendingIntent);