Java 8：计算两个LocalDateTime之间的差异 [英] Java 8: Calculate difference between two LocalDateTime
问题描述
我正在计算两个 LocalDateTime 之间的差异。
输出需要格式为 y年m个月d天h小时m分s秒。这是我写的：
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
public class Main {
static final int MINUTES_PER_HOUR = 60;
static final int SECONDS_PER_MINUTE = 60;
static final int SECONDS_PER_HOUR = SECONDS_PER_MINUTE * MINUTES_PER_HOUR;
public static void main（String [] args）{
LocalDateTime toDateTime = LocalDateTime.of（2014，9，9，19，46，45）;
LocalDateTime fromDateTime = LocalDateTime.of（1984，12，16，7，45，55）;
期间= getPeriod（fromDateTime，toDateTime）;
long time [] = getTime（fromDateTime，toDateTime）;
System.out.println（period.getYears（）+years+
period.getMonths（）+months+
period.getDays（）+days +
时间[0] +小时+
时间[1] +分钟+
时间[2] +秒）;
}
private static Period getPeriod（LocalDateTime dob，LocalDateTime now）{
return Period.between（dob.toLocalDate（），now。 toLocalDate（））;
}
private static long [] getTime（LocalDateTime dob，LocalDateTime now）{
LocalDateTime today = LocalDateTime.of（now.getYear（），
now。 getMonthValue（），now.getDayOfMonth（），dob.getHour（），dob.getMinute（），dob.getSecond（））;
持续时间=持续时间（今天，现在）;
long seconds = duration.getSeconds（）;
long hours = seconds / SECONDS_PER_HOUR;
long minutes =（（秒％SECONDS_PER_HOUR）/ SECONDS_PER_MINUTE）;
long secs =（seconds％SECONDS_PER_MINUTE）;
return new long [] {hours，minutes，secs};
}
}
我得到的输出是 29年8个月24天12小时0分50秒。我已从此（结果：29年，8个月，24天，12小时，0分钟和50秒）。
更新
由于我从两个不同的网站获得了两个不同的结果，我想知道如果我的计算算法是否合法。如果我使用以下两个 LocalDateTime 对象：
LocalDateTime toDateTime = LocalDateTime。 （2014，9，10，6，40，45）;
LocalDateTime fromDateTime = LocalDateTime.of（1984，12，16，7，45，55）;
然后输出即将到来： 29年8个月25天-1小时-5分-10秒。
从这个链接应该是 29年8个月24天22小时54分50秒。所以算法也需要处理负数。
注意问题不在于哪个网站给了我什么结果，我需要知道正确的算法和需要有正确的结果
不幸的是，似乎没有一个时间段，好吧，所以你可能需要自己做计算。
幸运的是，日期和时间类有很多实用方法可以在一定程度上简化。这是一种计算差异的方法，但不一定是最快的：
LocalDateTime fromDateTime = LocalDateTime.of（1984,12,16， 7，45，55）;
LocalDateTime toDateTime = LocalDateTime.of（2014，9，10，6，40，45）;
LocalDateTime tempDateTime = LocalDateTime.from（fromDateTime）;
long years = tempDateTime.until（toDateTime，ChronoUnit.YEARS）;
tempDateTime = tempDateTime.plusYears（years）;
long months = tempDateTime.until（toDateTime，ChronoUnit.MONTHS）;
tempDateTime = tempDateTime.plusMonths（months）;
long days = tempDateTime.until（toDateTime，ChronoUnit.DAYS）;
tempDateTime = tempDateTime.plusDays（days）;
long hours = tempDateTime.until（toDateTime，ChronoUnit.HOURS）;
tempDateTime = tempDateTime.plusHours（hours）;
long minutes = tempDateTime.until（toDateTime，ChronoUnit.MINUTES）;
tempDateTime = tempDateTime.plusMinutes（minutes）;
long seconds = tempDateTime.until（toDateTime，ChronoUnit.SECONDS）;
System.out.println（年+年+
个月+月+
天+天+
小时+小时+
分钟+分钟+
秒+秒）;
//印刷：29年8个月24天22小时54分50秒。
基本的想法是：创建一个临时的开始日期，并获得完整的年份。然后将该日期调整为年数，以便开始日期少于最后一年。对于每个时间单位，按降序重复。
最后一个免责声明：我没有考虑到不同的时区（两个日期应该在同一个时区），而我也没有测试/检查日历中的夏令时或其他更改（如萨摩亚的时区更改）如何影响此计算。所以请小心使用。
I am trying to calculate the difference between two LocalDateTime.
The output needs to be of the format y years m months d days h hours m minutes s seconds. Here is what I have written:
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
public class Main {
static final int MINUTES_PER_HOUR = 60;
static final int SECONDS_PER_MINUTE = 60;
static final int SECONDS_PER_HOUR = SECONDS_PER_MINUTE * MINUTES_PER_HOUR;
public static void main(String[] args) {
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 9, 19, 46, 45);
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
Period period = getPeriod(fromDateTime, toDateTime);
long time[] = getTime(fromDateTime, toDateTime);
System.out.println(period.getYears() + " years " +
period.getMonths() + " months " +
period.getDays() + " days " +
time[0] + " hours " +
time[1] + " minutes " +
time[2] + " seconds.");
}
private static Period getPeriod(LocalDateTime dob, LocalDateTime now) {
return Period.between(dob.toLocalDate(), now.toLocalDate());
}
private static long[] getTime(LocalDateTime dob, LocalDateTime now) {
LocalDateTime today = LocalDateTime.of(now.getYear(),
now.getMonthValue(), now.getDayOfMonth(), dob.getHour(), dob.getMinute(), dob.getSecond());
Duration duration = Duration.between(today, now);
long seconds = duration.getSeconds();
long hours = seconds / SECONDS_PER_HOUR;
long minutes = ((seconds % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
long secs = (seconds % SECONDS_PER_MINUTE);
return new long[]{hours, minutes, secs};
}
}
The output that I am getting is 29 years 8 months 24 days 12 hours 0 minutes 50 seconds. I have checked my result from this website (with values 12/16/1984 07:45:55 and 09/09/2014 19:46:45). The following screenshot shows the output:
I am pretty sure that the fields after the month value is coming wrong from my code. Any suggestion would be very helpful.
Update
I have tested my result from another website and the result I got is different. Here it is: Calculate duration between two dates (result: 29 years, 8 months, 24 days, 12 hours, 0 minutes and 50 seconds).
Update
Since I got two different results from two different sites, I am wondering if the algorithm of my calculation is legitimate or not. If I use following two LocalDateTime objects:
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 40, 45);
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
Then the output is coming: 29 years 8 months 25 days -1 hours -5 minutes -10 seconds.
From this link it should be 29 years 8 months 24 days 22 hours, 54 minutes and 50 seconds. So the algorithm needs to handle the negative numbers too.
Note the question is not about which site gave me what result, I need to know the right algorithm and need to have right results.
Unfortunately there doesn't seem to be a period class that spans time as well, so you might have to do the calculations on your own.
Forunately the date and time classes have a lot of utility methods that simplify that to some degree. Here's a way to calculate the difference although not necessarily the fastest:
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 40, 45);
LocalDateTime tempDateTime = LocalDateTime.from( fromDateTime );
long years = tempDateTime.until( toDateTime, ChronoUnit.YEARS);
tempDateTime = tempDateTime.plusYears( years );
long months = tempDateTime.until( toDateTime, ChronoUnit.MONTHS);
tempDateTime = tempDateTime.plusMonths( months );
long days = tempDateTime.until( toDateTime, ChronoUnit.DAYS);
tempDateTime = tempDateTime.plusDays( days );
long hours = tempDateTime.until( toDateTime, ChronoUnit.HOURS);
tempDateTime = tempDateTime.plusHours( hours );
long minutes = tempDateTime.until( toDateTime, ChronoUnit.MINUTES);
tempDateTime = tempDateTime.plusMinutes( minutes );
long seconds = tempDateTime.until( toDateTime, ChronoUnit.SECONDS);
System.out.println( years + " years " +
months + " months " +
days + " days " +
hours + " hours " +
minutes + " minutes " +
seconds + " seconds.");
//prints: 29 years 8 months 24 days 22 hours 54 minutes 50 seconds.
The basic idea is this: create a temporary start date and get the full years to the end. Then adjust that date by the number of years so that the start date is less then a year from the end. Repeat that for each time unit in descending order.
Finally a disclaimer: I didn't take different timezones into account (both dates should be in the same timezone) and I also didn't test/check how daylight saving time or other changes in a calendar (like the timezone changes in Samoa) affect this calculation. So use with care.
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