java日期相加减

import java.util.*;

import java.text.*;

public class formatDate {

public formatDate() {

}

// 格式化日期为字符串 "yyyy-MM-dd hh:mm"

public String formatDateTime(Date basicDate,String strFormat) {

SimpleDateFormat df = new SimpleDateFormat(strFormat);

return df.format(basicDate);

}

// 格式化日期为字符串 "yyyy-MM-dd hh:mm"

public String formatDateTime(String basicDate,String strFormat) {

SimpleDateFormat df = new SimpleDateFormat(strFormat);

Date tmpDate=null;

try {

tmpDate=df.parse(basicDate);

}

catch(Exception e) {

// 日期型字符串格式错误

}

return df.format(tmpDate);

}

// 当前日期加减n天后的日期，返回String (yyyy-mm-dd)

public String nDaysAftertoday(int n) {

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");

Calendar rightNow = Calendar.getInstance();

//rightNow.add(Calendar.DAY_OF_MONTH,-1);

rightNow.add(Calendar.DAY_OF_MONTH,+n);

return df.format(rightNow.getTime());

}

// 当前日期加减n天后的日期，返回String (yyyy-mm-dd)

public Date nDaysAfterNowDate(int n) {

Calendar rightNow = Calendar.getInstance();

//rightNow.add(Calendar.DAY_OF_MONTH,-1);

rightNow.add(Calendar.DAY_OF_MONTH,+n);

return rightNow.getTime();

}

// 给定一个日期型字符串，返回加减n天后的日期型字符串

public String nDaysAfterOneDateString(String basicDate,int n) {

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");

Date tmpDate = null;

try {

tmpDate = df.parse(basicDate);

}

catch(Exception e){

// 日期型字符串格式错误

}

long nDay=(tmpDate.getTime()/(24*60*60*1000)+1+n)*(24*60*60*1000);

tmpDate.setTime(nDay);

return df.format(tmpDate);

}

// 给定一个日期，返回加减n天后的日期

public Date nDaysAfterOneDate(Date basicDate,int n) {

long nDay=(basicDate.getTime()/(24*60*60*1000)+1+n)*(24*60*60*1000);

basicDate.setTime(nDay);

return basicDate;

}

// 计算两个日期相隔的天数

public int nDaysBetweenTwoDate(Date firstDate,Date secondDate) {

int nDay=(int)((secondDate.getTime()-firstDate.getTime())/(24*60*60*1000));

return nDay;

}

// 计算两个日期相隔的天数

public int nDaysBetweenTwoDate(String firstString,String secondString) {

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");

Date firstDate=null;

Date secondDate=null;

try {

firstDate = df.parse(firstString);

secondDate=df.parse(secondString);

}

catch(Exception e) {

// 日期型字符串格式错误

}

int nDay=(int)((secondDate.getTime()-firstDate.getTime())/(24*60*60*1000));

return nDay;

}

}