java 獲取當前天之后或之前7天日期

轉載：https://blog.csdn.net/guo_xiao_hui/article/details/70225447

/** 
    * 獲取過去或者未來 任意天內的日期數組 
    * @param intervals      intervals天內 
    * @return              日期數組 
    */  
   public static ArrayList<String> test(int intervals ) {  
       ArrayList<String> pastDaysList = new ArrayList<>();  
       ArrayList<String> fetureDaysList = new ArrayList<>();  
       for (int i = 0; i <intervals; i++) {  
           pastDaysList.add(getPastDate(i));  
           fetureDaysList.add(getFetureDate(i));  
       }  
       return pastDaysList;  
   }  
  
   /** 
    * 獲取過去第幾天的日期 
    * 
    * @param past 
    * @return 
    */  
   public static String getPastDate(int past) {  
       Calendar calendar = Calendar.getInstance();  
       calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past);  
       Date today = calendar.getTime();  
       SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");  
       String result = format.format(today);  
       Log.e(null, result);  
       return result;  
   }  
  
   /** 
    * 獲取未來 第 past 天的日期 
    * @param past 
    * @return 
    */  
   public static String getFetureDate(int past) {  
       Calendar calendar = Calendar.getInstance();  
       calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + past);  
       Date today = calendar.getTime();  
       SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");  
       String result = format.format(today);  
       Log.e(null, result);  
       return result;  
   }