Question

我一直试图解决这个数组超出范围的异常并且已经被困住了很长时间。

package mergesortmini;

public class MergeSortMini {
    public static void main(String[] args) {
        MergeSort m = new MergeSort();
        m.init().sort().printData();  
    }
}

class MergeSort {


   int[] data;


   public MergeSort init() {
      data = new int[10];
      data[0] = 5;
      data[1] = 67;
      data[2] = 0 - 12;
      data[3] = 7;
      data[4] = 1;
      data[5] = 2;
      data[6] = 99;
      data[7] = 3;
      data[8] = 4;
      data[9] = 67;
      return this;
   }


   public MergeSort sort() {
      data = this.mergeSort(data);
      return this;
   }

   public int printData() {
     int i = 0;  
     while(i < data.length){
         System.out.println(data[i]);
         i = i + 1;
     } 
     return data.length;
   }


   public int[] merge(int[] a1, int[] a2) {

       int lengthOfRes = a1.length + a2.length;
       int resArr[] = new int [lengthOfRes];    

       int a1Index = 0;
       int a2Index = 0;
       int resIndex = 0;

       while((a1Index < a1.length) || (a2Index < a2.length))
       {
           if((a1Index < a1.length) && (a2Index < a2.length)){

               if(a1[a1Index] < a2[a2Index]){
                   resArr[resIndex] = a1[a1Index];
                   a1Index = a1Index + 1;
                    resIndex = resIndex + 1;
               } else 
               {
                   resArr[resIndex] = a2[a2Index];
                   a2Index = a2Index + 1;
                   resIndex = resIndex + 1;
               }
           }
           else if(a1Index < a1.length){
                resArr[resIndex] = a1[a1Index];
                a1Index = a1Index + 1;
                resIndex = resIndex + 1;
           }
           else
           {
               resArr[resIndex] = a2[a2Index];
                a2Index = a2Index + 1;
                resIndex = resIndex + 1;
           }
       }
       return resArr;   
   }

   public int[] mergeSort(int[] arr) {

       if (arr.length < 2){
           return arr;  
       }
       int mid = arr.length / 2;  

       int leftArr[] = new int [mid];   
       int rightArr[];                 

        int halfLength = arr.length;
        if(isEven(halfLength))
        {
           rightArr = new int [mid];
        } 
        else 
        {
           rightArr = new int[mid + 1];
        }

       int resultArr[] = new int [arr.length];

       int i = 0;

       while(i < mid){  
           leftArr[i] = arr[i];
            i = i + 1;
       }
       int j = mid;
       int indexOfRight = 0;

       while(j < arr.length){
           rightArr[indexOfRight] = arr[j];
           indexOfRight = indexOfRight + 1; 
           j = j + 1;
       }

       leftArr = mergeSort(leftArr);
       rightArr = mergeSort(rightArr);

       return resultArr = merge(leftArr, rightArr);
   }

   public boolean isEven(int number){
        return (!((number - (number * 0.5) * 2) > 0)) && (!((number - (number * 0.5) * 2) < 0));
   }
}

控制台显示：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
    at mergesortmini.MergeSort.mergeSort(MergeSortMini.java:118)
    at mergesortmini.MergeSort.mergeSort(MergeSortMini.java:123)
    at mergesortmini.MergeSort.sort(MergeSortMini.java:33)
    at mergesortmini.MergeSortMini.main(MergeSortMini.java:6)

如果有人有任何建议，请帮助。

哦，只是提到我的项目规范声明我不能使用for循环，必须使用while，而且我只能使用选定数量的运算符。

我可以使用的运营商是：＆amp;＆amp; ＆LT; + - *

Answer 1

您的isEven方法已损坏：http://ideone.com/sMEQrP

你必须解决这个事实，即乘以一个浮点数会产生一个浮点数（所以它不像整数除法）：

public static boolean isEven(int number){
    return (!((number - (int)(number * 0.5) * 2) > 0)) 
        && (!((number - (int)(number * 0.5) * 2) < 0));
}

我该如何解决这个ArrayIndexOutOfBoundException？

1 个答案: