Timezone Poc

pocTimezone.java

package com.time;

import org.junit.Test;

import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.TimeZone;

import static java.time.LocalDateTime.ofInstant;
import static java.time.temporal.ChronoUnit.HOURS;
import static java.time.temporal.ChronoUnit.MINUTES;

public class TimezoneTest {

    @Test
    public void timezoneTest() {
        // from orderone
        String date = "2018-01-04T10:28";
        // from AIRPORTS in OLSON TIMEZONE
        String timezone = "Australia/Brisbane";

        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm");
        LocalDateTime parsedDate = LocalDateTime.parse(date, dateTimeFormatter);

        TimeZone timeZone = TimeZone.getDefault();
        System.out.println("Host timezone: " + timeZone.getDisplayName() + " (" + timeZone.getID() + ")");
        System.out.println("Flight departure: " + parsedDate);

        ZoneId brisbaneTimezone = ZoneId.of(timezone);

        ZonedDateTime brisbaneDateTime = parsedDate.atZone(brisbaneTimezone);
        System.out.println("Flight departure at Brisbane timezone: " + brisbaneDateTime);

        System.out.println("Flight departure at Brisbane timezone to Instant: " + brisbaneDateTime.toInstant());

        Instant now = Instant.now();
        System.out.println("Instant now: " + now);

        LocalDateTime localDateTime = ofInstant(now, brisbaneTimezone);

        System.out.println("Instant now at " + timezone + ": " + localDateTime);

        long minutesUntileFlightFromNow = localDateTime.until(brisbaneDateTime, MINUTES);

        long hoursUntileFlightFromNow = localDateTime.until(brisbaneDateTime, HOURS);

        long minutesLeft = minutesUntileFlightFromNow - (hoursUntileFlightFromNow * 60);

        System.out.println(minutesUntileFlightFromNow + " minutes (" + hoursUntileFlightFromNow + "h" + minutesLeft + "m) hours from departure");

        /*
            Host timezone: Central European Time (Europe/Rome)
            Flight departure: 2018-01-04T10:28
            Flight departure at Brisbane timezone: 2018-01-04T10:28+10:00[Australia/Brisbane]
            Flight departure at Brisbane timezone to Instant: 2018-01-04T00:28:00Z
            Instant now: 2018-01-03T17:34:46.066Z
            Instant now at Australia/Brisbane: 2018-01-04T03:34:46.066
            413 minutes (6h53m) hours from departure
         */
    }
}