Java Data Type - 如何在几小时内获得巴黎和伦敦之间的差异

import java.time.ZoneId;
import java.time.ZonedDateTime;

public class Main {
  public static void main(String[] argv) {
    ZonedDateTime paris = ZonedDateTime.now(ZoneId.of("Europe/Paris"));
    ZonedDateTime london = ZonedDateTime.now(ZoneId.of("Europe/London"));
    System.out.println(paris.getHour() - london.getHour());
  }
}