Java.util.Calendar - 自 1970 年 1 月 1 日以来的毫秒数 [英] Java.util.Calendar - milliseconds since Jan 1, 1970

问题描述

程序后跟输出.有人请向我解释为什么从 1970 年 1 月 1 日开始的 10,000,000 毫秒是 1969 年 11 月 31 日.好吧，请有人解释我的假设有什么问题，即第一次测试应该从 1970 年 1 月 1 日开始产生 10,000,000 毫秒的时间.小于 10,000,000 的数字产生同样的结果.

public static void main(String[] args) {字符串 x = "10000000";长 l = new Long(x).longValue();System.out.println("长值:" + l);日历 c = new GregorianCalendar();c.setTimeInMillis(l);System.out.println("以米为单位的日历时间:" + c.getTimeInMillis());字符串 origDate = c.get(Calendar.YEAR) + "-" + c.get(Calendar.MONTH) + "-" + c.get(Calendar.DAY_OF_MONTH);System.out.println("YYYY-MM-DD 格式的日期:" + origDate);x = "1000000000000";l = new Long(x).longValue();System.out.println("
长值:" + l);c.setTimeInMillis(l);System.out.println("以米为单位的日历时间:" + c.getTimeInMillis());origDate = c.get(Calendar.YEAR) + "-" + c.get(Calendar.MONTH) + "-" + c.get(Calendar.DAY_OF_MONTH);System.out.println("YYYY-MM-DD 格式的日期:" + origDate);}

<块引用>

长值:10000000

米利斯的日历时间:10000000

YYYY-MM-DD 格式的日期:1969-11-31

长值:1000000000000

米利斯的日历时间:1000000000000

YYYY-MM-DD 格式的日期:2001-8-8

解决方案

您从 Calendar 打印的日期是您所在时区的本地日期，而纪元定义为 1970-01-01 的午夜在UTC.因此，如果您居住在 UTC 以西的时区，那么您的日期将显示为 1969-12-31，即使(在 UTC 中)它仍然是 1970-01-01.

Program followed by output. Someone please explain to me why 10,000,000 milliseconds from Jan 1, 1970 is November 31, 1969. Well, someone please explain what's wrong with my assumption that the first test should produce a time 10,000,000 milliseconds from Jan 1, 1970. Numbers smaller than 10,000,000 produce the same result.

public static void main(String[] args) {

    String x = "10000000";
    long l = new Long(x).longValue();
    System.out.println("Long value: " + l);

    Calendar c = new GregorianCalendar();
    c.setTimeInMillis(l);
    System.out.println("Calendar time in Millis: " + c.getTimeInMillis());

    String origDate = c.get(Calendar.YEAR) + "-" + c.get(Calendar.MONTH) + "-" + c.get(Calendar.DAY_OF_MONTH);  
    System.out.println("Date in YYYY-MM-DD format: " + origDate);

    x = "1000000000000";
    l = new Long(x).longValue();
    System.out.println("
Long value: " + l);

    c.setTimeInMillis(l);
    System.out.println("Calendar time in Millis: " + c.getTimeInMillis());

    origDate = c.get(Calendar.YEAR) + "-" + c.get(Calendar.MONTH) + "-" + c.get(Calendar.DAY_OF_MONTH);  
    System.out.println("Date in YYYY-MM-DD format: " + origDate);
}

Long value: 10000000

Calendar time in Millis: 10000000

Date in YYYY-MM-DD format: 1969-11-31

Long value: 1000000000000

Calendar time in Millis: 1000000000000

Date in YYYY-MM-DD format: 2001-8-8

解决方案

The dates you print from Calendar are local to your timezone, whereas the epoch is defined to be midnight of 1970-01-01 in UTC. So if you live in a timezone west of UTC, then your date will show up as 1969-12-31, even though (in UTC) it's still 1970-01-01.

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