Trying to parse date and time in PDT into ZonedDateTime representation

The method expects in a specific format , eg . Since your input is in a different format, you will need . parse

String

2007-12-03T10:15:30+01:00[Europe/Paris]

DateTimeFormatter

It should be noted that the API uses IANA time zone names (always in the format Continent/City

such as America/Sao_Paulo

or Europe/Berlin

). Avoid using 3-letter abbreviations (for example, CST

or PST

) because they are ambiguous and not standard .

The API makes some exceptions with specific identifiers and provides some default values ​​for them. For, PDT

it defaults to America/Los_Angeles

.

Another detail is that in the example below, I used a lowercase hh

in the template: the format has an AM / PM indication, so I believe this hh

is the correct template since its value is from 1 to 12 (common values ​​when there is an AM / PM).

If you use an uppercase letter hh

, it allows values ​​from 0 to 23 (and this is not often used for use with AM / PM), but throws an exception if the input contains an hour, like07:00 PM

.

So, the code will look like this:

DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MM/dd/yyyy hh:mm a (zzz)");
ZonedDateTime z = ZonedDateTime.parse("06/24/2017 07:00 AM (PDT)", fmt);
System.out.println(z);

      

        
        
        
      

    

Output:

2017-06-24T07: 00-07: 00 [America / Los_Angeles]

But not all three-letter time zone names will be recognized by the API and will throw an exception.

Anyway, there are other timeslots that are also in the PDT (for example America/Vancouver

) - you can get a list of all by calling ZoneId.getAvailableZoneIds()

. If you want to use a different default timezone, you can create a set of preferred zones and build a formatter with that set:

Set<ZoneId> preferredZones = new HashSet<>();
// set America/Vancouver as preferred zone
preferredZones.add(ZoneId.of("America/Vancouver"));
DateTimeFormatter fmt = new DateTimeFormatterBuilder()
    // pattern
    .appendPattern("MM/dd/yyyy hh:mm a (")
    // append timezone with set of prefered zones
    .appendZoneText(TextStyle.SHORT, preferredZones)
    // finish the pattern
    .appendPattern(")")
    // create formatter
    .toFormatter();
System.out.println(ZonedDateTime.parse("06/24/2017 07:00 AM (PDT)", fmt));

      

        
        
        
      

    

The API will use the preferred zones (in this case America/Vancouver

) instead of the default ( America/Los_Angeles

). The output will be:

2017-06-24T07: 00-07: 00 [America / Vancouver]

It is not clear where the entrance came from String

. If you cannot control your format, then you have no choice: they have to be parsed that way. Then you can convert it to a different timezone using the method withZoneSameInstant

:

// parse the input string
ZonedDateTime z = ZonedDateTime.parse("06/24/2017 07:00 AM (PDT)", fmt);
// convert to another timezone
ZonedDateTime other = z.withZoneSameInstant(ZoneId.of("America/Sao_Paulo")); // 2017-06-24T11:00-03:00[America/Sao_Paulo]

      

        
        
        
      

    

The value other

will be 2017-06-24T11:00-03:00[America/Sao_Paulo]

.

But if you can control the output, it is always better (IMO) to work with UTC ( java.time.Instant

) and convert to some timezone only when displayed to users:

// convert ZonedDateTime to instant
ZonedDateTime z = // parse input
// convert to UTC (Instant is always in UTC)
Instant instant = z.toInstant();
// internally work with instant (as it always in UTC)

// convert instant to some timezone only when necessary (like displaying to users)
ZonedDateTime converted = instant.atZone(ZoneId.of("Europe/London"));