Question

我应该从＃34;人口中获得所有人口＃34;超过某个最小值的数组并将它们返回到数组中。我可以为我的新数组获取正确数量的元素，并正确分配最后一个值，但其余值将返回为零！

  class Canada {
        private String[] provinces; 
        private int[] populations; 
        private int[] array;
        private int i;

        public static final int NO_SUCH_PROVINCE = -1;
        public static final int O = 0; 
        public static final int Q = 1;
        public static final int BC = 2;
        public static final int A = 3;
        public static final int M = 4;
        public static final int S = 5;
        public static final int NS = 6;
        public static final int NB = 7;
        public static final int NL = 8;
        public static final int PE = 9;
        public static final int NT = 10;
        public static final int Y = 11;
        public static final int N = 12;

    public Canada() { 
        provinces = new String[13];
        provinces[O] = "Ontario";
        provinces[Q] = "Quebec";
        provinces[BC] = "British Columbia";
        provinces[A] = "Alberta";
        provinces[M] = "Manitoba";
        provinces[S] = "Saskatchewan";
        provinces[NS] = "Nova Scotia";
        provinces[NB]= "New Brunswick";
        provinces[NL] = "Newfoundland and Labrador";
        provinces[PE] = "Prince Edward Island";
        provinces[NT] = "Northwest Territories";
        provinces[Y] = "Yukon";
        provinces[N] = "Nunavut"; 

        populations = new int[13]; 
        populations[O] = 12851821;
        populations[Q] = 7903001;
        populations[BC] = 4400057;
        populations[A] = 3645257; 
        populations[M] = 1208268;
        populations[S] = 1033381;
        populations[NS] = 921727;
        populations[NB] = 751171;
        populations[NL] = 514536;
        populations[PE] = 142204;
        populations[NT] = 141462;
        populations[Y] = 33897;
        populations[N] = 31906;            
    }

    public int[] getPopulatiosnAboveMin(int min) {                          
        int i = 0;

        while(i < populations.length) {
            if(populations[i] > min){
                array = new int[i + 1];
              array[i] = populations[i];
            }
            i++;
        }    
        return(array);
    }    
  }

Answer 1

每次循环populations.length时，您都会重新创建数组。这就是为什么它最终只有一个值。

使用for-each循环尝试此代码（它有点乱，但它应该完成工作）：

   public int[] getPopulatiosnAboveMin(int min) {  

          int nextIndex = 0;
          int[] firstArray = new int[populations.length];

          //Copy values larger then min to firstArray
          for(int pop : populations) {
              if(pop > min) {
                  firstArray[nextIndex++] = pop;
              }
          }

          //Trim extra 0 values:

          //Count number of non 0 values:
          int non0Count = 0;
          for (int i : firstArray) {
              if (i != 0) {
                  non0Count++;
              }
          }

          array = new int[non0Count];   //Initialize array with count of valid, non-0 values.

          //Copy values from firstArray to array:
          int index = 0;
          for (int i : firstArray) {
              if (i != 0) {
                  array[index++] = i;
              }
          }

          return array;
        }

此外，正如评论中提到的SLaks，考虑创建一个代表您的省（和地区;））的类，或者查看使用地图，例如HashMap。

使用现有数组的元素填充数组

1 个答案: