java - Java方法来查找年，月和日的两个日期对象之间的差异

Question

我有一个开始日期和结束日期。两个日期之间的持续时间应采用年，月和日的形式。我是Java新手。
当我运行下面的方法时，我得到的是0年12个月1天。
请提出一种替代方案，以在几年，几个月和几天内获得准确的差异。

import java.sql.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

public class Duration {

    private String getAssignmentDuration(java.util.Date oldDate, java.util.Date newDate) {
        Calendar c1 = Calendar.getInstance();
        Calendar c2 = Calendar.getInstance();
        if (oldDate.compareTo(newDate) > 0) {
            c1.setTime(newDate);
            c2.setTime(oldDate);
        } else {
            System.out.println("invalid");
            return "Invalid selection";

        }
        int year = 0;
        int month = 0;
        int days = 0;
        boolean doneMonth = false;
        boolean doneYears = false;
        while (c1.before(c2)) {
            //log.debug("Still in Loop");
            if (!doneYears) {
                c1.add(Calendar.YEAR, 1);
                year++;
            }
            if (c1.after(c2) || doneYears) {
                if (!doneYears) {
                    doneYears = true;
                    year--;
                    c1.add(Calendar.YEAR, -1);
                }   
                if (!doneMonth) {
                    c1.add(Calendar.MONTH, 1);
                    month++;
                }
                if (c1.after(c2) || doneMonth) {
                    if (!doneMonth) {
                        doneMonth = true;
                        month--;
                        c1.add(Calendar.MONTH, -1);
                    }

                    c1.add(Calendar.DATE, 1);
                    days++;
                    if (c1.after(c2)) {
                        days--;
                    }
                    // this will not be executed
                    if (days == 31 || month==12) {
                        break;
                    }
                }
            }
        }
        System.out.println(year + " years, " + month + " months, " + days + " days");
        return year + " years, " + month + " months, " + days + " days";

    }


    public static void main(String[] args) {
        Duration d1= new Duration();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        java.util.Date oldDate = null;
        try {
            oldDate = sdf.parse("2012/08/29");
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        java.util.Date newDate = null;
        try {
            newDate = sdf.parse("2013/08/31");
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        d1.getAssignmentDuration(oldDate, newDate);
    }

}

Answer 1

 public static String getDateDifferenceInDDMMYYYY(Date from, Date to) {
        Calendar fromDate=Calendar.getInstance();
        Calendar toDate=Calendar.getInstance();
        fromDate.setTime(from);
        toDate.setTime(to);
        int increment = 0;
        int year,month,day;
        System.out.println(fromDate.getActualMaximum(Calendar.DAY_OF_MONTH));
        if (fromDate.get(Calendar.DAY_OF_MONTH) > toDate.get(Calendar.DAY_OF_MONTH)) {
            increment =fromDate.getActualMaximum(Calendar.DAY_OF_MONTH);
        }
         System.out.println("increment"+increment);
// DAY CALCULATION
        if (increment != 0) {
            day = (toDate.get(Calendar.DAY_OF_MONTH) + increment) - fromDate.get(Calendar.DAY_OF_MONTH);
            increment = 1;
        } else {
            day = toDate.get(Calendar.DAY_OF_MONTH) - fromDate.get(Calendar.DAY_OF_MONTH);
        }

// MONTH CALCULATION
        if ((fromDate.get(Calendar.MONTH) + increment) > toDate.get(Calendar.MONTH)) {
            month = (toDate.get(Calendar.MONTH) + 12) - (fromDate.get(Calendar.MONTH) + increment);
            increment = 1;
        } else {
            month = (toDate.get(Calendar.MONTH)) - (fromDate.get(Calendar.MONTH) + increment);
            increment = 0;
        }

// YEAR CALCULATION
        year = toDate.get(Calendar.YEAR) - (fromDate.get(Calendar.YEAR) + increment);
     return   year+"\tYears\t\t"+month+"\tMonths\t\t"+day+"\tDays";
    }

    public static void main(String[] args) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(1999,01,8);
       /*  Calendar calendar1 = Calendar.getInstance();
        calendar1.set(2012,01,23);*/
        System.out.println(getDateDifferenceInDDMMYYYY(calendar.getTime(),new Date()));
    }