Convert Japan date and time to your local timezone

import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class Main {
  public static void main(String[] argv) throws Exception {
    Calendar japanCal = new GregorianCalendar(TimeZone.getTimeZone("Japan"));
    japanCal.set(Calendar.HOUR_OF_DAY, 10); // 0..23
    japanCal.set(Calendar.MINUTE, 0);
    japanCal.set(Calendar.SECOND, 0);

    Calendar local = new GregorianCalendar();
    local.setTimeInMillis(japanCal.getTimeInMillis());
  }
}