查看示例http://www.roseindia.net/java/beginners/DateDifferent.shtml 这个例子给出了天、小时、分钟、秒和毫秒的差异:)。

import java.util.Calendar;
import java.util.Date;

public class DateDifferent {
    public static void main(String[] args) {
        Date date1 = new Date(2009, 01, 10);
        Date date2 = new Date(2009, 07, 01);
        Calendar calendar1 = Calendar.getInstance();
        Calendar calendar2 = Calendar.getInstance();
        calendar1.setTime(date1);
        calendar2.setTime(date2);
        long milliseconds1 = calendar1.getTimeInMillis();
        long milliseconds2 = calendar2.getTimeInMillis();
        long diff = milliseconds2 - milliseconds1;
        long diffSeconds = diff / 1000;
        long diffMinutes = diff / (60 * 1000);
        long diffHours = diff / (60 * 60 * 1000);
        long diffDays = diff / (24 * 60 * 60 * 1000);
        System.out.println("\nThe Date Different Example");
        System.out.println("Time in milliseconds: " + diff + " milliseconds.");
        System.out.println("Time in seconds: " + diffSeconds + " seconds.");
        System.out.println("Time in minutes: " + diffMinutes + " minutes.");
        System.out.println("Time in hours: " + diffHours + " hours.");
        System.out.println("Time in days: " + diffDays + " days.");
    }
}

注意:startDate和endDates为-> java.util.Date

import org.joda.time.Duration;
import org.joda.time.Interval;
// Use .getTime() unless it is a joda DateTime object
Interval interval = new Interval(startDate.getTime(), endDate.getTime());
Duration period = interval.toDuration();
//gives the number of days elapsed between start and end date.
period.getStandardDays();

与天类似，你也可以得到小时、分钟和秒

period.getStandardHours();
period.getStandardMinutes();
period.getStandardSeconds();

查看示例http://www.roseindia.net/java/beginners/DateDifferent.shtml 这个例子给出了天、小时、分钟、秒和毫秒的差异:)。

import java.util.Calendar;
import java.util.Date;

public class DateDifferent {
    public static void main(String[] args) {
        Date date1 = new Date(2009, 01, 10);
        Date date2 = new Date(2009, 07, 01);
        Calendar calendar1 = Calendar.getInstance();
        Calendar calendar2 = Calendar.getInstance();
        calendar1.setTime(date1);
        calendar2.setTime(date2);
        long milliseconds1 = calendar1.getTimeInMillis();
        long milliseconds2 = calendar2.getTimeInMillis();
        long diff = milliseconds2 - milliseconds1;
        long diffSeconds = diff / 1000;
        long diffMinutes = diff / (60 * 1000);
        long diffHours = diff / (60 * 60 * 1000);
        long diffDays = diff / (24 * 60 * 60 * 1000);
        System.out.println("\nThe Date Different Example");
        System.out.println("Time in milliseconds: " + diff + " milliseconds.");
        System.out.println("Time in seconds: " + diffSeconds + " seconds.");
        System.out.println("Time in minutes: " + diffMinutes + " minutes.");
        System.out.println("Time in hours: " + diffHours + " hours.");
        System.out.println("Time in days: " + diffDays + " days.");
    }
}

因为这个问题用Scala做了标记，

import scala.concurrent.duration._
val diff = (System.currentTimeMillis() - oldDate.getTime).milliseconds
val diffSeconds = diff.toSeconds
val diffMinutes = diff.toMinutes
val diffHours = diff.toHours
val diffDays = diff.toDays

一个稍微简单一点的选择:

System.currentTimeMillis() - oldDate.getTime()

至于“更好”，你到底需要什么?将时间持续时间表示为小时数和天数等的问题是，由于日期的复杂性，它可能导致不准确和错误的期望(例如，由于夏令时，一天可能有23或25小时)。

试试这个:

int epoch = (int) (new java.text.SimpleDateFormat("MM/dd/yyyy HH:mm:ss").parse("01/01/1970  00:00:00").getTime() / 1000);

你可以在parse()方法参数中编辑字符串。