java,取30天前的日期

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SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");String maxDateStr = "2017-02-08";String minDateStr = "";Calendar calc =Calendar.getInstance();try {calc.setTime(sdf.parse(maxDateStr));calc.add(calc.DATE, -30);Date minDate = calc.getTime();minDateStr = sdf.format(minDate);System.out.println("minDateStr:"+minDateStr);//minDateStr:2017-01-09   正确！！！！} catch (ParseException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}//SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");//String maxDateStr = "2017-02-08";//String minDateStr = "";//try {//Date minDate = new Date(sdf.parse(maxDateStr).getTime() - (30-1)*24*3600*1000);//minDateStr:2017-02-28   错误的！！！！！！//minDateStr = sdf.format(minDate);//System.out.println("minDateStr:"+minDateStr);  //"2017-02-06"<= ... <=  "2017-02-08"  //3天//} catch (ParseException e1) {//// TODO Auto-generated catch block//e1.printStackTrace();//}

前30天日期序列

 SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");          String maxDateStr = "2017-02-08";          String minDateStr = "";          Calendar calc =Calendar.getInstance();          try {              for(int i=0;i<30;i++){            calc.setTime(sdf.parse(maxDateStr));              calc.add(calc.DATE, -i);              Date minDate = calc.getTime();              minDateStr = sdf.format(minDate);              System.out.println(i+":minDateStr:"+minDateStr);//minDateStr:2017-01-09   正确！！！！              }        } catch (ParseException e1) {              // TODO Auto-generated catch block              e1.printStackTrace();          }

0:minDateStr:2017-02-08
1:minDateStr:2017-02-07
2:minDateStr:2017-02-06
3:minDateStr:2017-02-05
4:minDateStr:2017-02-04
5:minDateStr:2017-02-03
6:minDateStr:2017-02-02
7:minDateStr:2017-02-01
8:minDateStr:2017-01-31
9:minDateStr:2017-01-30
10:minDateStr:2017-01-29
11:minDateStr:2017-01-28
12:minDateStr:2017-01-27
13:minDateStr:2017-01-26
14:minDateStr:2017-01-25
15:minDateStr:2017-01-24
16:minDateStr:2017-01-23
17:minDateStr:2017-01-22
18:minDateStr:2017-01-21
19:minDateStr:2017-01-20
20:minDateStr:2017-01-19
21:minDateStr:2017-01-18
22:minDateStr:2017-01-17
23:minDateStr:2017-01-16
24:minDateStr:2017-01-15
25:minDateStr:2017-01-14
26:minDateStr:2017-01-13
27:minDateStr:2017-01-12
28:minDateStr:2017-01-11
29:minDateStr:2017-01-10

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