java - 数组相乘越界异常

Question

据我所知，这个程序是正确完成的。然而，考虑到异常(exception)情况，似乎并非如此。我要制作 2 个长度为 x(用户输入)的数组，并且用户要输入元素。完毕。接下来将每个元素乘以另一个数组中对应的元素，然后添加总和。

例如，数组1[0]*数组2[0] + 数组1[1]*数组2[1]...

精确的错误是:线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException:

我已经完成了许多不同的循环，下面我留出额外空间来识别的最后一个循环是我认为最接近正确但不正确的循环。我非常感谢您的建议，提前谢谢您。

   System.out.println("This program will multiply 2 one dimension arrays of any length. \n The length and contents of the array is entered from the keyboard.");
    System.out.println("Enther the data for the first array. ");

    System.out.println("Enther the length of the array (remember arrays being counting at 0, not 1:");

    int a = 0;
    Scanner keyboard = new Scanner(System.in);
    a = keyboard.nextInt();
    int[] firstArrayLength = new int[a];
    System.out.println("Enter the elements of the first array(remember arrays begin counting at 0, not 1");
    double arrayElements = 0;
    for (int elements = 0; elements <= firstArrayLength.length; elements++) {

        arrayElements = keyboard.nextInt();
    }

    System.out.println("Enter the data for the second array. ");
    System.out.println("Enter the elements of the second  array(remember arrays begin counting at 0, not 1");
    int[] secondArrayLength = new int[a];

    double secondArrayElements = 0;
    for (int elements = 0; elements <= secondArrayLength.length; elements++) {

        secondArrayElements = keyboard.nextInt();
    }
    double [] thirdArray = new double [a];





    for (int i =0; i <=firstArrayLength.length; i++)
       {
        thirdArray[a] = firstArrayLength[i]*secondArrayLength[i];
        }
    System.out.println(thirdArray);
        }

Answer 1

更改您的 <=符号至<当您访问数组时。例如:

for (int elements = 0; elements < firstArrayLength.length; elements++)
...

记住如果length是 4，您可以通过以下方式访问元素:

array[0], array[1], array[2], array[3] // 4 elements

array[4]不存在，导致 IndexOutOfBounds异常。

编辑

奇怪的输出 [I@756a7c99 (例如)是因为您将数组打印为:

int a[] = new int[4];
System.out.println(a);

相反，您可能想打印该数组的元素:

int a[] = new int[4];
for (int i = 0; i < 4; i++) {
    System.out.println(a[i]);
}

编辑2

public static void main(String[] args) {
    System.out
            .println("This program will multiply 2 one dimension arrays of any length. \n The length and contents of the array is entered from the keyboard.");
    System.out.println("Enther the data for the first array. ");

    System.out
            .println("Enther the length of the array (remember arrays being counting at 0, not 1:");

    int a = 0;
    Scanner keyboard = new Scanner(System.in);
    a = keyboard.nextInt();
    int[] firstArray = new int[a];
    System.out
            .println("Enter the elements of the first array(remember arrays begin counting at 0, not 1");
    for (int elements = 0; elements < firstArray.length; elements++) {

        firstArray[elements] = keyboard.nextInt();
    }

    System.out.println("Enter the data for the second array. ");
    System.out
            .println("Enter the elements of the second  array(remember arrays begin counting at 0, not 1");
    int[] secondArray = new int[a];

    for (int elements = 0; elements < secondArray.length; elements++) {

        secondArray[elements] = keyboard.nextInt();
    }
    double[] thirdArray = new double[a];

    for (int i = 0; i < firstArray.length; i++) {
        thirdArray[i] = firstArray[i]*secondArray[i];
    }

    for (int i = 0; i < thirdArray.length; i++)
        System.out.println(thirdArray[i]);
}