某日期多少天后的日期

Question

我现在有一日期 ，不是当前的日期，是一个不定日期（比如：2008-10-5）
求取：加上或者减去 几天后的日期 是哪一天

Answer 1

Date date = new SimpleDateFormat("yyyy-M-d").parse("2008-10-5");
Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.add(Calendar.DATE, 1);
date = cal.getTime();

Answer 2

http://www.xker.com/page/e2007/0614/26572_3.html
  这个说的详细一点   去看看

Answer 3

 import   java.util.Calendar;   
  import   java.util.Date;   
  import   java.text.*;   
    
    
  public   class   DateDealWith     
  {   
      public   DateDealWith(){       
      }   
          //取得系统当前时间,格式为yyyy-mm-dd   
      public   String   getCurrentDate(){   
                  Calendar   rightNow   =   Calendar.getInstance();   
                  int   year=rightNow.get(rightNow.YEAR);   
                  int   month=rightNow.get(rightNow.MONTH)+1;   
                  int   day=rightNow.get(rightNow.DATE);   
                  return   year+"-"+month+"-"+day;   
      }   
              //取得系统当前时间,格式为yyyy年mm月dd日   
      public   String   getCurrentDate1(){   
                  Calendar   rightNow   =   Calendar.getInstance();   
                  int   year=rightNow.get(rightNow.YEAR);   
                  int   month=rightNow.get(rightNow.MONTH)+1;   
                  int   day=rightNow.get(rightNow.DATE);   
                  return   year+"年"+month+"月"+day+"日";   
      }   
          //取得系统当前时间前n个月的相对应的一天   
      public   String   getNMonthBeforeCurrentDay(int   n){   
              Calendar   c   =   Calendar.getInstance();   
              c.add(c.MONTH,-n);   
              return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
    
      }   
          //取得系统当前时间后n个月的相对应的一天   
      public   String   getNMonthAfterCurrentDay(int   n){   
              Calendar   c   =   Calendar.getInstance();   
              c.add(c.MONTH,n);   
              return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
    
      }       
        
              //取得系统当前时间前n天,格式为yyyy-mm-dd   
      public   String   getNDayBeforeCurrentDate(int   n){   
                  Calendar   c   =   Calendar.getInstance();   
                  c.add(c.DAY_OF_MONTH,-n);   
                return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
      }   
                  //取得系统当前时间后n天,格式为yyyy-mm-dd   
      public   String   getNDayAfterCurrentDate(int   n){   
                  Calendar   c   =   Calendar.getInstance();   
                  c.add(c.DAY_OF_MONTH,n);   
                return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
      }   
      //---------------------------------------------------------------------   
              //取过去一个时间对应的系统当年的一天   
      public   String   getCurrentDateAfterPastDate(String   sPastDate){   
          if(sPastDate!=null   &&   !sPastDate.equals("")){   
              Date   date=switchStringToDate(sPastDate);   
              Calendar   c   =   Calendar.getInstance();   
              c.setTime(date);   
              int   iPastYear=c.get(c.YEAR);   
              Calendar   c1   =   Calendar.getInstance();   
              int   iCurrentYear=c1.get(c1.YEAR);   
              c.add(c.YEAR,iCurrentYear-iPastYear);   
              return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
          }else{   
              return   null;   
          }   
      }   
      //-----------------------------------------------------------------   
      //将一个日期字符串转化成日期   
      public   Date   switchStringToDate(String   sDate){   
            Date   date=null;   
            try{   
                SimpleDateFormat   df=new   SimpleDateFormat("yyyy-MM-dd");   
                date=df.parse(sDate);   
                  
            }catch(Exception   e){   
                System.out.println("日期转换失败:"+e.getMessage());   
            }   
            return   date;   
      }   
    
      //输入两个字符串型的日期，比较两者的大小   
      public   boolean   compareTwoDateBigOrSmall(String   fromDate,String   toDate){   
            Date   dateFrom   =   this.switchStringToDate(fromDate);   
            Date   dateTo   =   this.switchStringToDate(toDate);   
            if(dateFrom.before(dateTo)){   
                  return   true;   
            }else{   
                  return   false;   
            }   
      }   
        
      //将一个日期字符串转化成Calendar   
      public   Calendar   switchStringToCalendar(String   sDate){   
              Date   date   =   switchStringToDate(sDate);   
              Calendar   c   =   Calendar.getInstance();   
              c.setTime(date);   
              return   c;   
      }   
    //将一个日期转化成Calendar   
      public   Calendar   switchStringToCalendar(Date   date){   
              Calendar   c   =   Calendar.getInstance();   
              c.setTime(date);   
              return   c;   
      }   
  //------------------------------------------------------------------------   
          //取得某个时间前n个月的相对应的一天   
      public   String   getNMonthBeforeOneDay(String   sDate,int   n){   
              Calendar   c   =   switchStringToCalendar(sDate);   
              c.add(c.MONTH,-n);   
              return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
    
      }   
          //取得某个时间后n个月的相对应的一天   
      public   String   getNMonthAfterOneDay(String   sDate,int   n){   
              Calendar   c   =   switchStringToCalendar(sDate);   
              c.add(c.MONTH,n);   
              return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
    
      }       
        
              //取得某个时间前n天,格式为yyyy-mm-dd   
      public   String   getNDayBeforeOneDate(String   sDate,int   n){   
                  Calendar   c   =   switchStringToCalendar(sDate);   
                  c.add(c.DAY_OF_MONTH,-n);   
                return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
      }   
                  //取得某个时间后n天,格式为yyyy-mm-dd   
      public   String   getNDayAfterOneDate(String   sDate,int   n){   
                  Calendar   c   =   switchStringToCalendar(sDate);   
                  c.add(c.DAY_OF_MONTH,n);   
                return   ""+c.get(c.YEAR)+"-"+(c.get(c.MONTH)+1)+"-"+c.get(c.DATE);   
      }   
      //判断系统当前时间是不是润年   
      public   boolean   isRunNian(){   
        java.util.Calendar   rightNow   =   java.util.Calendar.getInstance();   
        int   year=rightNow.get(rightNow.YEAR);   
        if(0==year%4   &&   (year%100!=0   ||   year%400==0)){   
              return   true;         
        }else{   
              return   false;   
        }   
    
      }   
  }