Java如何计算两个日期之间的天数差异？
在下面的示例中，我们将计算两个日期之间的差异。首先，我们需要将日期转换为以毫秒为单位的相应值，然后进行数学计算，以便获得天，小时，分钟等之间的差异。
例如，要获取日差，我们将需要将毫秒差除以（24*60*60*1000）。
package org.nhooo.example.util;
import java.util.Calendar;
public class DateDifferenceExample {
public static void main(String[] args) {
//创建两个日历实例
Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
//设置两个日历实例的日期
cal1.set(2006, Calendar.DECEMBER, 30);
cal2.set(2007, Calendar.MAY, 3);
//获取表示的日期（以毫秒为单位）
long millis1 = cal1.getTimeInMillis();
long millis2 = cal2.getTimeInMillis();
//计算毫秒差
long diff = millis2 - millis1;
//计算差异（以秒为单位）
long diffSeconds = diff / 1000;
//以分钟为单位计算差异
long diffMinutes = diff / (60 * 1000);
//计算小时差
long diffHours = diff / (60 * 60 * 1000);
//计算天数差异
long diffDays = diff / (24 * 60 * 60 * 1000);
System.out.println("In milliseconds: " + diff + " milliseconds.");
System.out.println("In seconds: " + diffSeconds + " seconds.");
System.out.println("In minutes: " + diffMinutes + " minutes.");
System.out.println("In hours: " + diffHours + " hours.");
System.out.println("In days: " + diffDays + " days.");
}
}结果如下：
In milliseconds: 10713600000 milliseconds. In seconds: 10713600 seconds. In minutes: 178560 minutes. In hours: 2976 hours. In days: 124 days.
获取两个日期之间的天数的更好方法是使用JodaTimeAPI。在下面的示例中，您可以看到如何使用JodaTime计算日期差：如何获取JodaTime中两个日期之间的天数？