Getting current time in Java 8

Question

I am exploring the new java.time API of Java 8. I am particularly trying to retrieve the current time (my current time zone, of a different time zone, and of a different offset).

The code is:

public static void getCurrentLocalTime(){
    LocalTime time = LocalTime.now();
    System.out.println("Local Time Zone: "+ZoneId.systemDefault().toString());
    System.out.println("Current local time : " + time);
}

public static void getCurrentTimeWithTimeZone(){
    LocalDateTime localtDateAndTime = LocalDateTime.now();
    ZoneId zoneId = ZoneId.of("America/Los_Angeles");
    ZonedDateTime dateAndTimeInLA  = ZonedDateTime.of(localtDateAndTime, zoneId);
    String currentTimewithTimeZone =dateAndTimeInLA.getHour()+":"+dateAndTimeInLA.getMinute();
    System.out.println("Current time in Los Angeles: " + currentTimewithTimeZone);
}

public static void getCurrentTimeWithZoneOffset(){
    LocalTime localtTime = LocalTime.now();
    ZoneOffset offset = ZoneOffset.of("-08:00");
    OffsetTime  offsetTime  = OffsetTime.of(localtTime, offset);
    String currentTimewithZoneOffset =offsetTime.getHour()+":"+offsetTime.getMinute();
    System.out.println("Current time  with offset -08:00: " + currentTimewithZoneOffset);
}

But, when I call the methods I get the same time-of-day (my system time), which is obviously not what I am expecting.

The output of the method calls:

Current time in Los Angeles: 19:59
Local Time Zone: Asia/Calcutta
Current local time : 19:59:20.477
Current time  with offset -08:00: 19:59

Even after setting a different time zone and offset, why am I getting the same time?

Answer 1

LocalDateTime.now() always returns the current date/time in your default timezone (say 13 October @ 11.20am in London). When you create a ZonedDateTime or OffsetTime from it with a specific ZoneId or ZoneOffset, you get the same date and time but in a different time zone (for example 13 october at 11.20am in Los Angeles), which represents a different instant in time.

You are probably looking for something like:

Instant now = Instant.now();
ZoneId zoneId = ZoneId.of("America/Los_Angeles");
ZonedDateTime dateAndTimeInLA = ZonedDateTime.ofInstant(now, zoneId);

This will calculate the current date and time in Los Angeles: 13 october, 3.20am.