/**       * 得到本月的第一天       */      public static String getMonthFirstDay() {           Calendar calendar = Calendar.getInstance();           calendar.set(Calendar.DAY_OF_MONTH, calendar                   .getActualMinimum(Calendar.DAY_OF_MONTH)); //        calendar.set( Calendar.DATE, 1);        SimpleDateFormat simpleFormate = new SimpleDateFormat("yyyy-MM-dd");        return simpleFormate.format(calendar.getTime());       }             /**       * 得到本月的最后一天        */      public static String getMonthLastDay() {           Calendar calendar = Calendar.getInstance();           calendar.set(Calendar.DAY_OF_MONTH, calendar                   .getActualMaximum(Calendar.DAY_OF_MONTH));//        calendar.set( Calendar.DATE, 1);//        calendar.roll(Calendar.DATE, - 1);        SimpleDateFormat simpleFormate = new SimpleDateFormat("yyyy-MM-dd");        return simpleFormate.format(calendar.getTime());       }

获取某月的第一天和最后一天的日期

Calendar   ca   =   Calendar.getInstance();ca.setTime(someDate);                            //  someDate 为你要获取的那个月的时间ca.set(Calendar.DAY_OF_MONTH,   1);//第一天Date   firstDate   =   ca.getTime();ca.add(Calendar.MONTH,   1);ca.add(Calendar.DAY_OF_MONTH,   -1);//最后一天Date   lastDate   =   ca.getTime();