日期:2014-05-20  浏览次数:20939 次

JAVA中如何得到两个日期相减的月数???急!!
JAVA中如何得到两个日期相减的月数???
我用如下函数得到的月数有问题:
public int getMonthNum(Date date1,Date date2) {
Calendar cal1=Calendar.getInstance();
cal1.setTime(date1);
Calendar cal2=Calendar.getInstance();
cal2.setTime(date2);
return (cal2.get(1)-cal1.get(1))*12+(cal2.get(2)-cal1.get(2));
}
例如用2012-7-30减去2012-8-2 得到的月数为1;
用2012-7-31进去2012-7-1得到的月数为0


该怎么写才能精确的计算两个日期相减的月数呢???????????


------解决方案--------------------
你这样的要求不是很简单吗?
Java code

int m = date1.getMonth()-date1.getMonth();

------解决方案--------------------
再加上年
Java code

int m = (date1.getYear()-date2.getYear())*12+date1.getMonth()-date1.getMonth();

------解决方案--------------------
不明白你这个精确的意思!!!!给个例子?
------解决方案--------------------
加上年
------解决方案--------------------
Java code
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MonthTest{

    public static void main(String[] args) throws ParseException {
        String d1 = "2012-01-12";
        String d2 = "2010-02-11";
        SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");
        Calendar c = Calendar.getInstance();
        c.setTime(sdf.parse(d1));
        int year1 = c.get(Calendar.YEAR);
        int month1 = c.get(Calendar.MONTH);
        
        c.setTime(sdf.parse(d2));
        int year2 = c.get(Calendar.YEAR);
        int month2 = c.get(Calendar.MONTH);
        
        int result;
        if(year1 == year2) {
            result = month1 - month2;
        } else {
            result = 12*(year1 - year2) + month1 - month2;
        }
        System.out.println(result);
    }
}

------解决方案--------------------
顶,楼上回答正确
------解决方案--------------------
探讨

Java code
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MonthTest{

public static void main(String[] args) throws ParseException {
……

------解决方案--------------------
楼主我懂你!!!分给我吧
把两个日期都化成秒,然后再相减~~~
JAVA中以某个时刻为0秒,具体可以去查API!
其实日期就是以秒储存的,显示时再转化过来。
代码蛮简单呀~马上吃饭了~要不等会贴代码?
------解决方案--------------------
Java code

public int getMonthNum(Date date1,Date date2) {
Calendar cal1=Calendar.getInstance();
cal1.setTime(date1);
Calendar cal2=Calendar.getInstance();
cal2.setTime(date2);
long millis1=cal1.getTimeInMillis();
long millis2=cal2.getTimeInMillis();
long millis;
(millis1>millis2)?(millis=millis1-millis2):(millis=millis2-millis1);//java能这么写吗?忘记了!反正是判断谁大谁小,不能这样写就自己改下吧~~
Calendar cal=Calendar.getInstance();
cal.setTimeInMillis(millis);
return (cal.get(1)*12+cal.get(2));
}

------解决方案--------------------
上面12月是11打漏了。。。
------解决方案--------------------
keithcai兄弟讲的没太明白
我也来个比较笨的方法,年月日都可以算

Java code

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class Test {

    public static void main(String[] args) throws Exception {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        long time1 = sdf.parse("2012-01-12").getTime();
        long time2 = sdf.parse("2010-02-11").getTime();
        System.out.println(getFieldDifference(time1, time2, Calendar.YEAR));
        System.out.println(getFieldDifference(time1, time2, Calendar.MONTH));
        System.out.println(getFieldDifference(time1, time2, Calendar.DATE));
    }

    /**
     * 区分两个日期之间指定字段的差值
     * 
     * @param time1
     *            开始时间
     * @param time2
     *            结束时间
     * @param field
     *            要比较的字段(年,月,日,...)
     * @return 如果time1>time2就反回一个正的差值,如果time1<time2则返回一个负的差值,如果相等,返回0
     */
    public static int getFieldDifference(long time1, long time2, int field) {
        if (time1 == time2) {
            return 0;
        } else if (time1 > time2) {
            return -getFieldDifference(time2, time1, field);
        }
        Calendar cal1 = Calendar.getInstance();
        cal1.setLenient(false);
        cal1.setTimeInMillis(time1);
        Calendar cal2 = Calendar.getInstance();
        cal2.setLenient(false);
        cal2.setTimeInMillis(time2);
        for (int x = 0; x < Calendar.FIELD_COUNT; x++) {
            if (x > field) {
                cal1.clear(x);
                cal2.clear(x);
            }
        }
        time1 = cal1.getTimeInMillis();
        time2 = cal2.getTimeInMillis();

        long ms = 0;
        int min = 0, max = 1;

        while (true) {
            cal1.setTimeInMillis(time1);
            cal1.add(field, max);
            ms = cal1.getTimeInMillis();
            if (ms == time2) {
                min = max;
                break;
            } else if (ms > time2) {
                break;
            } else {
                max <<= 1;
            }
        }

        while (max > min) {
            cal1.setTimeInMillis(time1);
            int t = (min + max) >>> 1;
            cal1.add(field, t);
            ms = cal1.getTimeInMillis();
            if (ms == time2) {
                min = t;
                break;
            } else if (ms > time2) {
                max = t;
            } else {
                min = t;
            }
        }
        return -min;
    }

}