我试图计算两个LocalDateTime之间的差异。

输出格式为y年m个月d天h小时m分s秒。以下是我所写的:

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);

        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};
    }
}

我得到的输出是29年8个月24天12小时0分50秒。我已经从这个网站检查了我的结果(值12/16/1984 07:45:55和09/09/2014 19:46:45)。输出结果如下截图所示:

我非常确定,月份值之后的字段在我的代码中是错误的。任何建议都会很有帮助。

更新

我从另一个网站测试了我的结果,得到的结果是不同的。计算两个日期之间的持续时间(结果:29年8个月24天12小时0分50秒)。

更新

由于我从两个不同的网站得到了两个不同的结果,我想知道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.of(2014, 9, 10, 6, 40, 45);
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);

然后输出来了:29年8个月25天-1小时-5分-10秒。

从这个环节开始应该是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,这个问题不是关于哪个站点给了我什么结果,我需要知道正确的算法,需要有正确的结果。


当前回答

乔达时间

由于许多答案需要API 26支持,而我的最小API是23,我用下面的代码解决了它:

import org.joda.time.Days

LocalDate startDate = Something
LocalDate endDate = Something
// The difference would be exclusive of both dates, 
// so in most of use cases we may need to increment it by 1
Days.daysBetween(startDate, endDate).days

其他回答

对于你的问题,我有一个很简单的回答。它的工作原理。

import java.time.*;
import java.util.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;

public class MyClass {
public static void main(String args[]) {
    DateTimeFormatter T = DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm");
    Scanner h = new Scanner(System.in);

    System.out.print("Enter date of birth[dd/mm/yyyy hh:mm]: ");
    String b = h.nextLine();

    LocalDateTime bd = LocalDateTime.parse(b,T);
    LocalDateTime cd = LocalDateTime.now();

    long minutes = ChronoUnit.MINUTES.between(bd, cd);
    long hours = ChronoUnit.HOURS.between(bd, cd);

    System.out.print("Age is: "+hours+ " hours, or " +minutes+ " minutes old");
}
}

塔帕斯玻色码和托马斯码存在一些问题。如果time differenс为负值,则array获得负值。例如,如果

LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 46, 45);
LocalDateTime fromDateTime = LocalDateTime.of(2014, 9, 9, 7, 46, 45);

它返回0年0月1天-1小时0分0秒。

我认为正确的输出是:0年0月0天23小时0分0秒。

我建议在LocalDate和LocalTime实例上分离LocalDateTime实例。之后,我们可以获得Java 8 Period和Duration实例。Duration实例根据天数和全天时间值(< 24h)进行分离,并对周期值进行后续更正。当第二个LocalTime值在第一个LocalTime值之前时,需要将周期缩短一天。

下面是我计算LocalDateTime差异的方法:

private void getChronoUnitForSecondAfterFirst(LocalDateTime firstLocalDateTime, LocalDateTime secondLocalDateTime, long[] chronoUnits) {
    /*Separate LocaldateTime on LocalDate and LocalTime*/
    LocalDate firstLocalDate = firstLocalDateTime.toLocalDate();
    LocalTime firstLocalTime = firstLocalDateTime.toLocalTime();

    LocalDate secondLocalDate = secondLocalDateTime.toLocalDate();
    LocalTime secondLocalTime = secondLocalDateTime.toLocalTime();

    /*Calculate the time difference*/
    Duration duration = Duration.between(firstLocalDateTime, secondLocalDateTime);
    long durationDays = duration.toDays();
    Duration throughoutTheDayDuration = duration.minusDays(durationDays);
    Logger.getLogger(PeriodDuration.class.getName()).log(Level.INFO,
            "Duration is: " + duration + " this is " + durationDays
            + " days and " + throughoutTheDayDuration + " time.");

    Period period = Period.between(firstLocalDate, secondLocalDate);

    /*Correct the date difference*/
    if (secondLocalTime.isBefore(firstLocalTime)) {
        period = period.minusDays(1);
        Logger.getLogger(PeriodDuration.class.getName()).log(Level.INFO,
                "minus 1 day");
    }

    Logger.getLogger(PeriodDuration.class.getName()).log(Level.INFO,
            "Period between " + firstLocalDateTime + " and "
            + secondLocalDateTime + " is: " + period + " and duration is: "
            + throughoutTheDayDuration
            + "\n-----------------------------------------------------------------");

    /*Calculate chrono unit values and  write it in array*/
    chronoUnits[0] = period.getYears();
    chronoUnits[1] = period.getMonths();
    chronoUnits[2] = period.getDays();
    chronoUnits[3] = throughoutTheDayDuration.toHours();
    chronoUnits[4] = throughoutTheDayDuration.toMinutes() % 60;
    chronoUnits[5] = throughoutTheDayDuration.getSeconds() % 60;
}

上述方法可用于计算任何本地日期和时间值的差值,例如:

public long[] getChronoUnits(String firstLocalDateTimeString, String secondLocalDateTimeString) {
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    LocalDateTime firstLocalDateTime = LocalDateTime.parse(firstLocalDateTimeString, formatter);
    LocalDateTime secondLocalDateTime = LocalDateTime.parse(secondLocalDateTimeString, formatter);

    long[] chronoUnits = new long[6];
    if (secondLocalDateTime.isAfter(firstLocalDateTime)) {
        getChronoUnitForSecondAfterFirst(firstLocalDateTime, secondLocalDateTime, chronoUnits);
    } else {
        getChronoUnitForSecondAfterFirst(secondLocalDateTime, firstLocalDateTime, chronoUnits);
    }
    return chronoUnits;
}

为上述方法编写单元测试很方便(它们都是PeriodDuration类成员)。代码如下:

@RunWith(Parameterized.class)
public class PeriodDurationTest {

private final String firstLocalDateTimeString;
private final String secondLocalDateTimeString;
private final long[] chronoUnits;

public PeriodDurationTest(String firstLocalDateTimeString, String secondLocalDateTimeString, long[] chronoUnits) {
    this.firstLocalDateTimeString = firstLocalDateTimeString;
    this.secondLocalDateTimeString = secondLocalDateTimeString;
    this.chronoUnits = chronoUnits;
}

@Parameters
public static Collection<Object[]> periodValues() {
    long[] chronoUnits0 = {0, 0, 0, 0, 0, 0};
    long[] chronoUnits1 = {0, 0, 0, 1, 0, 0};
    long[] chronoUnits2 = {0, 0, 0, 23, 0, 0};
    long[] chronoUnits3 = {0, 0, 0, 1, 0, 0};
    long[] chronoUnits4 = {0, 0, 0, 23, 0, 0};
    long[] chronoUnits5 = {0, 0, 1, 23, 0, 0};
    long[] chronoUnits6 = {29, 8, 24, 12, 0, 50};
    long[] chronoUnits7 = {29, 8, 24, 12, 0, 50};
    return Arrays.asList(new Object[][]{
        {"2015-09-09 21:46:44", "2015-09-09 21:46:44", chronoUnits0},
        {"2015-09-09 21:46:44", "2015-09-09 22:46:44", chronoUnits1},
        {"2015-09-09 21:46:44", "2015-09-10 20:46:44", chronoUnits2},
        {"2015-09-09 21:46:44", "2015-09-09 20:46:44", chronoUnits3},
        {"2015-09-10 20:46:44", "2015-09-09 21:46:44", chronoUnits4},
        {"2015-09-11 20:46:44", "2015-09-09 21:46:44", chronoUnits5},
        {"1984-12-16 07:45:55", "2014-09-09 19:46:45", chronoUnits6},
        {"2014-09-09 19:46:45", "1984-12-16 07:45:55", chronoUnits6}
    });
}

@Test
public void testGetChronoUnits() {
    PeriodDuration instance = new PeriodDuration();
    long[] expResult = this.chronoUnits;
    long[] result = instance.getChronoUnits(this.firstLocalDateTimeString, this.secondLocalDateTimeString);
    assertArrayEquals(expResult, result);
}

}

无论第一个LocalDateTime值是否在任何LocalTime值之前或之前,所有测试都是成功的。

五年多后,我回答了我的问题。我认为持续时间为负的问题可以通过简单的修正来解决:

LocalDateTime fromDateTime = LocalDateTime.of(2014, 9, 9, 7, 46, 45);
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 46, 45);

Period period = Period.between(fromDateTime.toLocalDate(), toDateTime.toLocalDate());
Duration duration = Duration.between(fromDateTime.toLocalTime(), toDateTime.toLocalTime());

if (duration.isNegative()) {
    period = period.minusDays(1);
    duration = duration.plusDays(1);
}
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);
long time[] = {hours, minutes, secs};
System.out.println(period.getYears() + " years "
            + period.getMonths() + " months "
            + period.getDays() + " days "
            + time[0] + " hours "
            + time[1] + " minutes "
            + time[2] + " seconds.");

注意:https://www.epochconverter.com/date-difference现在可以正确计算时差了。

谢谢大家的讨论和建议。

不幸的是,似乎没有一个period类也可以跨越时间,所以您可能必须自己进行计算。

幸运的是,日期和时间类有很多实用程序方法,在某种程度上简化了这一点。这里有一个计算差异的方法,虽然不一定是最快的:

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( 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.

基本的想法是这样的:创建一个临时的开始日期,并得到完整的年份结束。然后按年数调整该日期,使开始日期距离结束日期少于一年。按降序对每个时间单位重复上述操作。

最后一个免责声明:我没有考虑不同的时区(两个日期应该在同一个时区),我也没有测试/检查夏令时或日历中的其他变化(比如萨摩亚的时区变化)如何影响这个计算。所以要小心使用。

Groovy中@Thomas的版本将所需的单位放在列表中,而不是硬编码值。这个实现(可以很容易地移植到Java -我将函数声明显式)使Thomas方法更具可重用性。

def fromDateTime = LocalDateTime.of(1968, 6, 14, 0, 13, 0)
def toDateTime = LocalDateTime.now()
def listOfUnits = [
    ChronoUnit.YEARS, ChronoUnit.MONTHS, ChronoUnit.DAYS,
    ChronoUnit.HOURS, ChronoUnit.MINUTES, ChronoUnit.SECONDS,
    ChronoUnit.MILLIS]

println calcDurationInTextualForm(listOfUnits, fromDateTime, toDateTime)    

String calcDurationInTextualForm(List<ChronoUnit> listOfUnits, LocalDateTime ts, LocalDateTime to)
{
    def result = []

    listOfUnits.each { chronoUnit ->
        long amount = ts.until(to, chronoUnit)
        ts = ts.plus(amount, chronoUnit)

        if (amount) {
            result << "$amount ${chronoUnit.toString()}"
        }
    }

    result.join(', ')
}

在撰写本文时,上面的代码返回47年8个月9天22小时52分7秒140 Millis。并且,对于@Gennady Kolomoets输入,代码返回23 Hours。

当你提供一个单位列表时,它必须按单位的大小排序(最大的优先):

def listOfUnits = [ChronoUnit.WEEKS, ChronoUnit.DAYS, ChronoUnit.HOURS]
// returns 2495 Weeks, 3 Days, 8 Hours