Convert next cron time in UTC format

Question

My database has times in UTC format. When I fetch from the database it comes in a long datatype format. For eg

In DB - 2023-03-08 15:01:05.234081
Corresponding Long - 1678258865

I am having a cron expression and trying to determine the next time to be run for the particular data. For eg, the next run should be at 2023-03-09 15:00:00.234081 UTC for the above data.

    long prevRun = 1678258865L;
    final CronExpression cronExpression = new CronExpression("0 1 0 * * ?");
    cronExpression.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
    Date date = Date.from(Instant.ofEpochSecond(prevRun)); => Outputs Tue Mar 07 23:01:05 PST 2023
    Date nextRun = cronExpression.getNextValidTimeAfter(prevRun); => Outputs Wed Mar 08 16:01:00 PST 2023

The fourth line always gives in the local system time zone which is why the cron gives this output. Any advice on how I can get a new run in UTC time format for the above cron expression? I am using a cron quartz expression parser for my current use case.

Answer 1

Good night friend

    long prevRun = 1678298465L; // is Wed Mar 08 15:01:05 BRT
    final CronExpression cronExpression = new CronExpression("0 1 18 * * ?");
    cronExpression.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
    Date date = Date.from(Instant.ofEpochSecond(prevRun)); 
    Date nextRun = cronExpression.getNextValidTimeAfter(date);
    System.out.println(date);        // Wed Mar 08 15:01:05 BRT 2023
    System.out.println(nextRun);     // Thu Mar 09 15:01:00 BRT 2023