如果startDate和endDate是java.util.Date的实例

我们可以从ChronoUnit enum中使用between()方法:

public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive) {
    //..
}

ChronoUnit。DAYS表示完成24小时的天数。

import java.time.temporal.ChronoUnit;

ChronoUnit.DAYS.between(startDate.toInstant(), endDate.toInstant());

//OR 

ChronoUnit.DAYS.between(Instant.ofEpochMilli(startDate.getTime()), Instant.ofEpochMilli(endDate.getTime()));

使用最能满足您需求的类或方法:

Duration类， 周期类, 或者ChronoUnit。之间的方法。

Duration使用基于时间的值(秒、纳秒)度量时间量。

Period使用基于日期的值(年、月、日)。

ChronoUnit。当您希望仅以单个时间单位(如天或秒)测量时间量时，Between方法非常有用。

https://docs.oracle.com/javase/tutorial/datetime/iso/period.html

如果你想要逻辑日历日，请使用java.time.temporal.ChronoUnit中的days .between()方法:

LocalDate dateBefore;
LocalDate dateAfter;
long daysBetween = DAYS.between(dateBefore, dateAfter);

如果你想要24小时的天，(一个duration)，你可以使用duration类:

LocalDate today = LocalDate.now()
LocalDate yesterday = today.minusDays(1);
// Duration oneDay = Duration.between(today, yesterday); // throws an exception
Duration.between(today.atStartOfDay(), yesterday.atStartOfDay()).toDays() // another option

更多信息请参考本文档。

使用枚举java.time.temporal.ChronoUnit中的DAYS。下面是示例代码:

输出: *开始日期:2015-03-01到结束日期:2016-03-03的天数为==> 368。 **开始日期:2016-03-03到结束日期:2015-03-01之间的天数==> -368*

package com.bitiknow.date;

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

/**
 * 
 * @author pradeep
 *
 */
public class LocalDateTimeTry {
    public static void main(String[] args) {

        // Date in String format.
        String dateString = "2015-03-01";

        // Converting date to Java8 Local date
        LocalDate startDate = LocalDate.parse(dateString);
        LocalDate endtDate = LocalDate.now();
        // Range = End date - Start date
        Long range = ChronoUnit.DAYS.between(startDate, endtDate);
        System.out.println("Number of days between the start date : " + dateString + " and end date : " + endtDate
                + " is  ==> " + range);

        range = ChronoUnit.DAYS.between(endtDate, startDate);
        System.out.println("Number of days between the start date : " + endtDate + " and end date : " + dateString
                + " is  ==> " + range);

    }

}

date是java.util.Date的实例

public static long daysBetweenTwoDates(Date dateFrom, Date dateTo) {
            return DAYS.between(Instant.ofEpochMilli(dateFrom.getTime()), Instant.ofEpochMilli(dateTo.getTime()));
        }

如果目标只是得到天的差异，而且既然上面的答案提到了关于委托方法，想指出的是，一旦也可以简单地使用-

public long daysInBetween(java.time.LocalDate startDate, java.time.LocalDate endDate) {
  // Check for null values here

  return endDate.toEpochDay() - startDate.toEpochDay();
}