int类型转换成String ， 不足n位 在前面补0

1.String.format("%02d", 5);-->结果：05

0代表前面要补的字符

2代表字符串长度

d表示参数为整数类型

2.秒转换成时分秒

 private String secToTime(int time){

         String timeStr = null;

         int hour = 0;

         int minute = 0;

         int second = 0;

         if (time <= 0)

             return "00:00";

         else {

             minute = time / 60;

             if (minute < 60) {

                 second = time % 60;

                 timeStr = String.format("%02d", minute) + ":" + String.format("%02d", second);

             } else {

                 hour = minute / 60;

                 if (hour > 99)

                     return "99:59:59";

                 minute = minute % 60;

                 second = time - hour * 3600 - minute * 60;

                 timeStr = String.format("%02d", hour) + ":" + String.format("%02d", minute) + ":" + String.format("%02d", second);

             }

         }

         return timeStr;

     }