在本教程中，我们将看到如何计算两个日期之间的差异。
有时我们有要求找到没有。
两个日期或者否之间的日子。
两个日期之间的几个小时。

Java程序：

package com.org.igi.theitroad;
 
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
 
/**
 * @author theitroad.com
 * igi Mandliya
 * 
 */
public class DateDiff {
 
    public static void main(String[] args) {
        try {
            String date1 = "04/21/2015";
            String date2 = "04/24/2015";
     
            String format = "MM/dd/yyyy";
 
            SimpleDateFormat sdf = new SimpleDateFormat(format);
            Date dateObj1 = sdf.parse(date1);
            Date dateObj2 = sdf.parse(date2);
            
            System.out.println("Date 1:"+dateObj1);
            System.out.println("Date 2:"+dateObj2 + "n");
 
            //For thousand separator
            DecimalFormat decimalFormatter = new DecimalFormat("###,###");
 
            long diffInMilliSeconds = dateObj2.getTime() - dateObj1.getTime();
 
            System.out.println("difference in milliseconds: " + decimalFormatter.format(diffInMilliSeconds));
            
            int diffsec = (int) (diffInMilliSeconds/(1000));
            System.out.println("difference in seconds: " + decimalFormatter.format(diffsec));
            
            int diffInMin = (int) (diffInMilliSeconds/(60 * 1000));
            System.out.println("difference in minutes: " + decimalFormatter.format(diffInMin));
            
            int diffInHours = (int) (diffInMilliSeconds/(60 * 60 * 1000));
            System.out.println("difference in hours: " + decimalFormatter.format(diffInHours));
            
            int diffInDays = (int) (diffInMilliSeconds/(24 * 60 * 60 * 1000));
            System.out.println("difference in days: " + diffInDays);
 
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行上面的程序时，我们将获取以下输出：

Date 1:Thu Apr 21 00:00:00 IST 2015
Date 2:Sun Apr 24 00:00:00 IST 2015
 
difference in milliseconds: 259,200,000
difference between seconds: 259,200
difference in minutes: 4,320
difference in hours: 72
difference in days: 3