date - Compare two time continously in android -

i want run async task in android every intervals.

my interval = { 15 min , 30 min , 1 hour ....etc

depending on users' choice.

when start application want fetch current time , after every n interval want execute async task

   int intv = 15;    simpledateformat sd = new simpledateformat(             "hh:mm:ss");     date date = new date();     sd.settimezone(timezone.gettimezone("gmt+05:30"));     system.out.println(sd.format(date));     string currenttime = sd.format(date);     date mydatetime = null;     try       {         mydatetime = sd.parse(currenttime);       }     catch (parseexception e)       {          e.printstacktrace();       }     system.out.println("this actual        date:"+sd.format(mydatetime));     calendar cal = new gregoriancalendar();     cal.settime(mydatetime);              cal.add(calendar.minute , intv ); //here adding interval     system.out.println("this hours added date:"+sd.format(cal.gettime()));     try {         date afterintv = sd.parse(sd.format(cal.gettime()));         if(afterintv.after(mydatetime)){  //here comparing              system.out.println("true..........");             new sendingtask().execute;  //this function have execute         }     } catch (parseexception e) {         // todo auto-generated catch block         e.printstacktrace();     } 

but not getting how do.

if want run asynctask after sometime can use thread.sleep in asynctask. in case sendingtask class. here sample:

class sendingtask extends asynctask{      // interval in milliseconds     int interval = 1000;      public sendingtask(int interval) {         // setting delay before executed         this.interval = interval;     }      @override     protected object doinbackground(object[] params) {         // wait according interval         try {             thread.sleep(interval);         } catch (interruptedexception e) {             e.printstacktrace();         }         return null;     }      @override     protected void onpostexecute(object o) {         super.onpostexecute(o);         // update ui , restart asynctask         textview3.settext("true..........");         new sendingtask(3000).execute();     } }