我在Scala中使用Java的Java .util.Date类,并希望比较Date对象和当前时间。我知道我可以通过使用getTime()来计算delta:
(new java.util.Date()).getTime() - oldDate.getTime()
然而,这只给我留下一个长表示毫秒。有没有更简单,更好的方法来得到时间?
我在Scala中使用Java的Java .util.Date类,并希望比较Date对象和当前时间。我知道我可以通过使用getTime()来计算delta:
(new java.util.Date()).getTime() - oldDate.getTime()
然而,这只给我留下一个长表示毫秒。有没有更简单,更好的方法来得到时间?
当前回答
不使用标准API,不行。你可以这样做:
class Duration {
private final TimeUnit unit;
private final long length;
// ...
}
或者你可以使用Joda:
DateTime a = ..., b = ...;
Duration d = new Duration(a, b);
其他回答
public static String getDifferenceBtwTime(Date dateTime) {
long timeDifferenceMilliseconds = new Date().getTime() - dateTime.getTime();
long diffSeconds = timeDifferenceMilliseconds / 1000;
long diffMinutes = timeDifferenceMilliseconds / (60 * 1000);
long diffHours = timeDifferenceMilliseconds / (60 * 60 * 1000);
long diffDays = timeDifferenceMilliseconds / (60 * 60 * 1000 * 24);
long diffWeeks = timeDifferenceMilliseconds / (60 * 60 * 1000 * 24 * 7);
long diffMonths = (long) (timeDifferenceMilliseconds / (60 * 60 * 1000 * 24 * 30.41666666));
long diffYears = (long)(timeDifferenceMilliseconds / (1000 * 60 * 60 * 24 * 365));
if (diffSeconds < 1) {
return "one sec ago";
} else if (diffMinutes < 1) {
return diffSeconds + " seconds ago";
} else if (diffHours < 1) {
return diffMinutes + " minutes ago";
} else if (diffDays < 1) {
return diffHours + " hours ago";
} else if (diffWeeks < 1) {
return diffDays + " days ago";
} else if (diffMonths < 1) {
return diffWeeks + " weeks ago";
} else if (diffYears < 12) {
return diffMonths + " months ago";
} else {
return diffYears + " years ago";
}
}
int daysDiff = (date1.getTime() - date2.getTime()) / MILLIS_PER_DAY;
在阅读了许多关于这个问题的回答和评论后,我的印象是,要么使用Joda时间,要么考虑到日光节约时间的一些特点等等。由于这两种方法我都不想做,所以我最终编写了几行代码来计算两个日期之间的差异,而没有使用任何与日期或时间相关的Java类。
在下面的代码中,年、月和日的数字与现实生活中的数字相同。例如,2015年12月24日,年= 2015,月= 12,日= 24。
我想分享这些代码,以防其他人想要使用它。有3种方法:1)找出给定年份是否是闰年的方法2)计算给定年份1月1日的天数的方法3)计算任意两个日期之间天数的方法2(结束日期减去开始日期)。
方法如下:
1)
public static boolean isLeapYear (int year) {
//Every 4. year is a leap year, except if the year is divisible by 100 and not by 400
//For example 1900 is not a leap year but 2000 is
boolean result = false;
if (year % 4 == 0) {
result = true;
}
if (year % 100 == 0) {
result = false;
}
if (year % 400 == 0) {
result = true;
}
return result;
}
2)
public static int daysGoneSince (int yearZero, int year, int month, int day) {
//Calculates the day number of the given date; day 1 = January 1st in the yearZero
//Validate the input
if (year < yearZero || month < 1 || month > 12 || day < 1 || day > 31) {
//Throw an exception
throw new IllegalArgumentException("Too many or too few days in month or months in year or the year is smaller than year zero");
}
else if (month == 4 || month == 6 || month == 9 || month == 11) {//Months with 30 days
if (day == 31) {
//Throw an exception
throw new IllegalArgumentException("Too many days in month");
}
}
else if (month == 2) {//February 28 or 29
if (isLeapYear(year)) {
if (day > 29) {
//Throw an exception
throw new IllegalArgumentException("Too many days in month");
}
}
else if (day > 28) {
//Throw an exception
throw new IllegalArgumentException("Too many days in month");
}
}
//Start counting days
int days = 0;
//Days in the target month until the target day
days = days + day;
//Days in the earlier months in the target year
for (int i = 1; i < month; i++) {
switch (i) {
case 1: case 3: case 5:
case 7: case 8: case 10:
case 12:
days = days + 31;
break;
case 2:
days = days + 28;
if (isLeapYear(year)) {
days = days + 1;
}
break;
case 4: case 6: case 9: case 11:
days = days + 30;
break;
}
}
//Days in the earlier years
for (int i = yearZero; i < year; i++) {
days = days + 365;
if (isLeapYear(i)) {
days = days + 1;
}
}
return days;
}
3)
public static int dateDiff (int startYear, int startMonth, int startDay, int endYear, int endMonth, int endDay) {
int yearZero;
//daysGoneSince presupposes that the first argument be smaller or equal to the second argument
if (10000 * startYear + 100 * startMonth + startDay > 10000 * endYear + 100 * endMonth + endDay) {//If the end date is earlier than the start date
yearZero = endYear;
}
else {
yearZero = startYear;
}
return daysGoneSince(yearZero, endYear, endMonth, endDay) - daysGoneSince(yearZero, startYear, startMonth, startDay);
}
如果你想修复跨越夏时制边界的日期范围的问题(例如,一个日期在夏季,另一个日期在冬季),你可以使用这个来获得天数的差异:
public static long calculateDifferenceInDays(Date start, Date end, Locale locale) {
Calendar cal = Calendar.getInstance(locale);
cal.setTime(start);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
long startTime = cal.getTimeInMillis();
cal.setTime(end);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
long endTime = cal.getTimeInMillis();
// calculate the offset if one of the dates is in summer time and the other one in winter time
TimeZone timezone = cal.getTimeZone();
int offsetStart = timezone.getOffset(startTime);
int offsetEnd = timezone.getOffset(endTime);
int offset = offsetEnd - offsetStart;
return TimeUnit.MILLISECONDS.toDays(endTime - startTime + offset);
}
不幸的是,JDK Date API被严重破坏了。我推荐使用Joda Time库。
Joda Time有一个时间间隔的概念:
Interval interval = new Interval(oldTime, new Instant());
编辑:顺便说一下,Joda有两个概念:Interval表示两个时间瞬间之间的时间间隔(表示上午8点到上午10点之间的时间),Duration表示没有实际时间边界的时间长度(例如表示两个小时!)
如果你只关心时间比较,大多数Date实现(包括JDK)实现了Comparable接口,允许你使用Comparable. compareto ()