World Clock
Print the current time in all time zones known to the JDK (from the tz
database) together with their
current UTC offset and the DST status.
Since Java 8
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class WorldClock {
static final DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("E, yyyy-MM-dd HH:mm:ss xxx", Locale.US);
String format(ZonedDateTime t) {
String dst = t.getZone().getRules().isDaylightSavings(t.toInstant()) ? "DST" : "";
return "%-32s %s %s".formatted(t.getZone(), t.format(FORMATTER), dst);
}
void main() {
Instant now = Instant.now();
ZoneId.getAvailableZoneIds().stream() //
.map(ZoneId::of) //
.map((ZoneId z) -> ZonedDateTime.ofInstant(now, z)) //
.sorted() //
.map(this::format).forEach(IO::println);
}
}
This snippet at GitHub