个人记录--当前年月，求当月天数和上月

String yearMon="201506"
Calendar c =Calendar.getInstance();
         c.set(Calendar.YEAR,Integer.parseInt(yearMon.substring(0, 4)));
         c.set(Calendar.MONTH,Integer.parseInt(yearMon.substring(4, 6))-1);
         int days= c.getActualMaximum(Calendar.DAY_OF_MONTH);//获取当月的天数
         c.set(Calendar.DATE,days);
         SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
         String lastDate = sdf.format(c.getTime());//获取当月最后一天
         c.clear(Calendar.DATE);
         c.add(Calendar.MONTH,-1);
         String lastMonth = new SimpleDateFormat("yyyyMM").format(c.getTime());