配列を既存の配列の要素に代入する

Question

"population"配列のすべての集団を特定の最小値以上にして配列に戻すことになっています。私は私の新しい配列の要素の正しい量を取得し、最後の値を正しく割り当てることができますが、残りの値は0に戻ります！

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

populations.lengthをループするたびに、アレイを再作成します。だからこそ、1つの価値だけで終わるのです。

for-eachループを使用してこのコードを試してみてください（これは少し厄介だが、それは仕事を得る必要があります）：SLaksはコメントで述べたように

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; 
     } 

また、（あなたの州を表すためにクラスを作成することを検討地域）;））、またはHashMapなどのマップを使用して見てください。