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;
     }