java - Arraylist 到整数数组，无法正常工作(java)!

Question

我正在创建一种方法来取数组中所有偶数的平均值。

如何将 arraylist 对象 (evens) 转换为数组，以便对它们求和？

    public static double percentEven(int[]a)
    {
    ArrayList evens = new ArrayList();
    int evenSum = 0;


    for (int counter = 0;counter < a.length;counter++)
    {
        if ((a[counter]%2) == 0 )    
        evens.add(a[counter]);
    }    

    int[] evenReturned = new int[evens.size()];
    evens.toArray(evenReturned);

    int evensCount = 0;
    for (evensCount = 0;evensCount < evens.size();evensCount++)
    {
        evenSum += evenReturned[evensCount];   
    }    


    return evenSum/evensCount;

  }    

Answer 1

你为什么要收集它们？把它们加起来!

int evensCount = 0;
int evenSum = 0;
for (int counter = 0; counter < a.length; counter++) {
    if (a[counter] % 2 == 0) {
        evensCount++;
        evenSum += a[counter];
    }
}

return evenSum/evensCount;