public static void radix_sortin(int[] str) {
  
  // 桶  10个桶  每个桶的最大容量默认为数组长度
  int[][] bucket = new int[10][str.length];
  // 每个桶的当前容量
  int[] capacity = new int[10];
       
  //元素求出最大数                                                                                                                                                                                                                                                                                                                                                                                                                                          
  int max = str[0];
  for (int r = 0; r < str.length; r++) {
   if (str[r] > max) {
    max = str[r];
   }
  }
  //求出最大长度 用于判断循环几大轮 
  int length = (max + "").length();
       
      //取得（个位 十位 百位。。。。）基数     
  for (int b= 0,u=1; b < length; b++,u*=10) {
   for (int i = 0; i < str.length; i++) {
    int base = str[i] /u % 10;  //比如基数为 4
    //将基数按照规则放进桶中
    bucket[base][capacity[base]] = str[i];     //放进第四个桶中 的第一几个当前容量位置
    capacity[base]++;   //容量增加
   }
   
   // 取出数据
   int d = 0;
   for (int k = 0; k < capacity.length; k++) {
    if (capacity[k] != 0) {
     for (int p = 0; p < capacity[k]; p++) {
      str[d] = bucket[k][p];
      d++;
     }
    }
    //注意：清零
    capacity[k] = 0;
   }

  }
 }