inDaylightTime（）问题，并确定日期是否在夏令时 [英] Issue with inDaylightTime() and determing if a date is in daylight savings time

问题描述

对此一直心存怀疑，不确定在这里做错了什么。

Have been beating my head against this and not sure what I'm doing wrong here.

我正在一定时间范围内测试inDaylightTime（）方法但在这种情况下应返回 true时返回 false。

I am testing out the inDaylightTime() method for a certain time zone but it is returning "false" when it should be returning "true" in this case.

import java.util.TimeZone;
import java.util.Date;

public class TimeZoneDemo {
    public static void main( String args[] ){

        Date date = new Date(1380931200); // Sat, 05 Oct 2013, within daylight savings time.

        System.out.println("In daylight saving time: " + TimeZone.getTimeZone("GMT-8:00").inDaylightTime(date));
    }    
}

当看起来很清楚时，此代码将继续打印 false

This code keeps printing "false" when it seems clear that the result should be "true".

我在这里错过了什么？希望获得任何指导。

What am I missing here? Would appreciate any guidance.

推荐答案

您指定的时区为 GMT-8：00 -这是一个固定时区，比UTC 永久晚8个小时。

You're specifying a time zone of GMT-8:00 - that's a fixed time zone, which is 8 hours behind of UTC permanently. It doesn't observe daylight saving time.

如果您实际上是指太平洋时间，则应指定 America / Los_Angeles 作为时区ID。请记住，一年中的不同时间会在标准时间和夏时制之间切换不同的时间。

If you actually meant Pacific Time, you should specify America/Los_Angeles as the time zone ID. Bear in mind that different time zones switch between standard and daylight saving time at different times of the year.

此外，新日期（1380931200）实际上是1970年1月-您的意思是新日期（1380931200000L）-不要忘记该数字为毫秒 Unix时代，而不是 seconds 。

Additionally, new Date(1380931200) is actually in January 1970 - you meant new Date(1380931200000L) - don't forget that the number is milliseconds since the Unix epoch, not seconds.

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