for语句中的java索引超出范围

Question

我在运行时遇到一个错误：“索引数组超出范围”，但我找不到位置。该程序假设取25个随机数，将它们分成偶数和奇数，并显示单独的组。我调试了第一个语句，这很好，这是我的第二个语句，但我不知道为什么。两个数组元素不能相等吗

public class EvensandOdds {



 public static void main(String[] args)  {

    int i;
    int countEven = 0;
    int countOdd = 0;
    int num;
    int numEven = 0;
    int numOdd = 0;
    int [] evenNum;
    int [] oddNum;
    int [] ranNum = new int[25];


    for (i = 0; i <= 24; i++) {
        num = (int) (100 * Math.random());
        ranNum[i] = num;
        if (num % 2 == 0) {
            numEven += 1;
        } else numOdd += 1;
    }

    evenNum = new int[numEven];
    oddNum = new int [numOdd];

    for (i = 0; i <= 24; i++) {
        if (ranNum[i] % 2 == 0) {
            evenNum[countEven] = ranNum[i]; //This separates the two groups into different arrays. Is this a valid statement?
            countEven += 1;
        } else oddNum[countOdd] = ranNum[i];
        countOdd += 1;
    }

    System.out.print("Your even numbers are: \n");
    for (i = 0; i <= countEven; i++) {
        System.out.print(evenNum[i]);
    }

    System.out.print("Your odd numbers are: \n");
    for (i = 0; i <= countOdd; i++) {
        System.out.print(oddNum[i]);
    }



 }
}

Answer 1

1. countOdd += 1对偶数和奇数都执行，请尝试更改以下行：

   } else oddNum[countOdd] = ranNum[i];
    countOdd += 1;
   

   进入：

   } else { 
       oddNum[countOdd] = ranNum[i];
       countOdd += 1; 
   }
   

2. 更改（如Lion建议的）

   for (i = 0; i <= countEven; i++) {
   

   及

   for (i = 0; i <= countOdd; i++) {
   

   进入

   for (i = 0; i < countEven; i++) {
   

   及

   for (i = 0; i < countOdd; i++) {
   

Answer 2

oddNum数组长度为8。。。但使用较大的countOdd，这会导致第行出现异常：

oddNum[countOdd] = ranNum[i];

导致此问题的原因是countOdd+=1；不包含在括号内，如：

else addNum[countOdd++] = ranNum[i];

Answer 3

countOdd += 1;语句不在一对大括号内，因此即使数字为偶数，也会执行它

} else { 
    oddNum[countOdd] = ranNum[i];
    countOdd += 1; 
}

这将解决您的错误