java - Start task using calendar object where just the second is set -

using below code, i'm attempting start thread when second part of time reaches 0 - ie when next minute starts.

public class sched {         public static void main(string args[]) {         calendar calstart = calendar.getinstance(timezone.gettimezone("gmt+1"));         calstart.set(calendar.second, 0);            scheduledexecutorservice scheduler = executors.newscheduledthreadpool(1);         scheduler.scheduleatfixedrate(new sched().new rc(), calstart.gettime().gettime(), 3, timeunit.seconds);     }      private class rc implements runnable {         public void run() { /* impl */}         } } 

but thread not starting. appears not setting start time correctly. run setting initialdelay param 0, why setting using calendar object not working?

fyi, hardcoding initialdelay 0 works (tested on jdk8):

scheduler.scheduleatfixedrate(new sched().new rc(), 0, 3, timeunit.seconds); 

i don't know why you're using calendar object (actually, don't know why anyone use one, that's story).

try using integer arithmetic on current time calculate number of seconds till next minute:

scheduler.scheduleatfixedrate(new sched().new rc(),      60 - system.currenttimemillis() / 1000 % 60, 3, timeunit.seconds); 

timezone irrelevant code, since seconds part of date same no matter timezone you're in.