Java.util.Calendar未正确更新时区

1cosmwyk 于 2022-10-01 发布在 Java

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此方法的目标是获取UTC日期，将其转换为指定的时区并返回DateTimeValue对象。然而，我们最近在某些时区使用此方法时发现了一个错误。

private static DateTimeValue toDateTimeValue(Date endDate, TimeZone timeZone) {     
    Calendar cal = Calendar.getInstance();
    cal.setTime(endDate);
    cal.setTimeZone(timeZone);
    cal.set(Calendar.HOUR_OF_DAY, 23); // move to the end of the day
    cal.set(Calendar.MINUTE, 59);
    cal.set(Calendar.SECOND, 59);
    int year = cal.get(Calendar.YEAR);
    int month = cal.get(Calendar.MONTH) + 1;
    int day = cal.get(Calendar.DAY_OF_MONTH);  //ends up being 3 but should be 4
    int hour = cal.get(Calendar.HOUR_OF_DAY);
    int minute = cal.get(Calendar.MINUTE);
    int second = cal.get(Calendar.SECOND);

    return new DateTimeValueImpl(year, month, day, hour, minute, second);
}

说明错误的主要案例：

结束日期值：星期一OCT 03 21：00：00 UTC 2022
时区值：欧洲/赫尔辛基+3

在上面的方法中，日期值最终是第3天，但它应该是第4天，因为UTC中的03月21：00：00实际上是赫尔辛基时区的10月4日

我用这个代码代替那个方法做了一些进一步的测试。

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    String utcDate = sdf.format(endDate); 
    System.out.println(utcDate);   //2022-10-03 09:00:00

    sdf.setTimeZone(timeZone);
    String timeZoneDate = sdf.format(endDate);
    System.out.println(timeZoneDate);   //2022-10-04 12:00:00

这显示了正确/预期的结果，但这是一个字符串，我需要将其作为DateTimeValue。

为什么当我们将时区设置为赫尔辛基时，java.util.calar不更新日期(日期)？

Java

来源：https://stackoverflow.com/questions/73912411/java-util-calendar-not-updating-the-timezone-properly

1条答案

按热度按时间

y1aodyip1#

The java.util date-time API is outdated and error-prone. It is recommended to stop using them completely and switch to the modern date-time API.

The following demo shows how easily and cleanly you could do/test it by using the modern date-time API.

Demo:

public class Main {
    public static void main(String[] args) {
        ZonedDateTime endDate = ZonedDateTime.of(LocalDate.of(2022, 10, 3), LocalTime.of(21, 0), ZoneOffset.UTC);
        ZonedDateTime zdtDesired = endDate.withZoneSameInstant(ZoneId.of("Europe/Helsinki"));
        System.out.println(zdtDesired);
        System.out.println(zdtDesired.getDayOfMonth());
    }
}

Output:

2022-10-04T00:00+03:00[Europe/Helsinki]
4

How to convert `java.util.Date` into `ZonedDateTime`?

You can convert java.util.Date into Instant which can be converted into ZonedDateTime. It means you do not even need to use ZonedDateTime#withZoneSameInstant as shown in the above demo.

public class Main {
    public static void main(String[] args) {
        // In your case, it will be endDate.toInstant()
        Instant instant = new Date().toInstant();
        ZonedDateTime zdtDesired = instant.atZone(ZoneId.of("Europe/Helsinki"));
        System.out.println(zdtDesired);
    }
}

Output:

2022-09-30T21:57:50.487+03:00[Europe/Helsinki]

Learn more about the the modern date-time API from**Trail: Date Time**.

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Java.util.Calendar未正确更新时区

1条答案

How to convert `java.util.Date` into `ZonedDateTime`?

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Java.util.Calendar未正确更新时区

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How to convert java.util.Date into ZonedDateTime?

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How to convert `java.util.Date` into `ZonedDateTime`?