Question

我不得不为学校编写这个程序来增加一对二维数组。我不停地越界：当我尝试运行程序时出现3错误。

我已经多次查看过这段代码，并且不能为我的生活找出故障发生的地方。我运行了一个调试，第一个断点位于if语句“if（a [0] .length！= b.length）”我无法弄清楚为什么这是一个断点。

有人可以帮助我吗？

    public class Multiply {

    public static double[][] Multiply_2D_Arrays(double[][] a, double[][] b)

    { 
        if (a[0].length != b.length) // Check to see if the number of a's colums equals the number of b's rows
        {
            throw new IllegalArgumentException("Matrices don't match: " + a[0].length + " != " + b.length);

        }

        int a_rows = a.length;      // Defines the variable M as the row length of array a
        int b_columns = b[0].length;   // Defines the variable N as the column length of array b
        double[][] c = new double[a_rows][b_columns]; // This means that the dimensions of array c will be the rows of a by the columns of b

        for(int i = 0; i < a.length; i++)
            {
                for(int j = 0; j < b[0].length; j++)
                {
                    for(int k = 0; k < a[0].length; )
                    {

                        c[i][j] += a[i][k] * b[k][j];     //Iterates through each row and column of array a and b and then adding it to the dot point sum

                    }

                }
            }

            return c;      //returns the final new array c

        }

    public static void main(String[] args)

    {
        double[][] array1 = {{4.0, 5.0, 6.0}, {2.0, 1.0, 4.0}, {8.0, 7.0, 6.0}, {1.0, 1.0, 2.0}};
        double[][] array2 = {{5.0, 7.0, 7.0, 8.0}, {8.0, 8.0, 9.0, 2.0}, {10.0, 2.0, 3.0, 1.0}};
        double[][] array3 = Multiply.Multiply_2D_Arrays(array1, array2); //Calls the Multiply_2D_Arrays method

        for(int i = 0; i < array3.length; i++)
        {
            for (int j = 0; j < array3.length; j++)
            {
                System.out.print(array3[i][j] + " ");
            }
        }

        System.out.println();
    }

}

Answer 1

你错过了k++ for(int k = 0; k < a[0].length; )

然后你有一个无限循环

此外，如果您想将结果打印为矩阵，请将System.out.println()放入for循环：

    for(int i = 0; i < array3.length; i++)
    {
        for (int j = 0; j < array3.length; j++)
        {
            System.out.print(array3[i][j] + " ");
        }
        System.out.println();
    }

Answer 2

如果您将此for(int k = 0; k < a[0].length; )更改为for(int k = 0; k < a[0].length;k++ )错过k++内圈for循环，程序将正确执行。

Java二维数组乘法错误？

2 个答案: