将新的 HashSet 添加到先前的 HashSet，"CHANGING" 先前的 HashSet 并继续这样做直到满足特定条件

Question

我知道如果你有两个 HashSet 你可以创建第三个添加 two.However，为了我的目的我需要改变我以前的 HashSet，寻找某些condition ，然后如果不满足则更改设置 again.My 目的是我将给出一个输入，比如数字 456，并查找数字（1 到 9，包括 0）。如果我'我找不到 HashSet 的尺寸 10 然后我将数字乘以 2 ，然后执行 same.So 我会得到 912;现在大小是 6（我需要得到所有数字 1-9 和 0，即大小 10）。现在我将它乘以 3 得到 2736，大小现在是 7.I继续这样做，直到我得到大小 10.At 当我得到大小 10 时，我将完成循环并且 return 结束循环的最后一个数字，按照增量乘法 rule.My 方法是follows.It 有错误所以不会运行但它代表了我目前的理解。

 public long digitProcessSystem(long N) {
  // changing the passed in number into String 
  String number = Long.toString(N);
 //splitting the String so that I can investigate each digit
  String[] arr = number.split("");
// Storing the digits(which are Strings now) into HashSet
  Set<String> input = new HashSet<>(Arrays.asList(arr));
// Count starts for incremental purpose later.
  count =1;
 //When I get all digits; 1-9, & 0, I need to return the last number that concluded the condition
     while (input.size() == 10) {
         return N;
     }
// The compiler telling me to delete the else but as a new Java user so far my understanding is that I can use `else` with `while`loops.Correct me if I'm missing something.
     else {
          // Increment starts following the rule; N*1, N*2,N*3,...till size is 10
          N = N*count;
         // doing everything over
          String numberN = Long.toString(N);
          String[] arr1 = number.split("");
         // need to change the previous `input`so that the new updated `HashSet` gets passed in the while loop to look for size 10.This is error because I'm using same name `input`. But I don't want to create a new `set` , I need to update the previous `set` which I don't know how.
          Set<String> input = new HashSet<>(Arrays.asList(arr1));
       // increments count  
       count++;

     }

Answer 1

clear() input 并添加新值。像

// Set<String> input = new HashSet<>(Arrays.asList(arr1));
input.clear();
input.addAll(Arrays.asList(arr1));

和

while (input.size() == 10) {

应该是

if (input.size() == 10) {

或者您的 else 未绑定到 if。

将新的 HashSet 添加到先前的 HashSet，"CHANGING" 先前的 HashSet 并继续这样做直到满足特定条件

Add a new HashSet to a previous HashSet, "CHANGING" the previous HashSet and continue doing so until certain condition has been met

java

hashset