java 中的二维数组

Question

我想编写一个 java 程序来打印二维数组每一行的平均值，但它仅适用于第一行。我不知道是什么问题。

这是代码：

    int [][] A = new int[r][c];

    for (int i=0;i<A.length;i++)
    {
        System.out.println("Enter the elements of the row number: "+(i+1));
        for (int j=0; j<A[i].length;j++)
            A[i][j]=kbd.nextInt();
    }

    int sum = 0, avg =0;
    for (int i=0; i<A.length;i++)
    {
        for (int j=0; j<A[i].length;j++) {
            sum += A[i][j];
            avg = sum/A[i].length;
        }
        
        System.out.println("The average of the row number: "+(i+1)+" is: "+avg);
    }

}

Answer 1

每次循环都需要将总和重置为零。这可以通过在 for 循环内部而不是外部声明 sum 变量来解决。另外 avg 和 sum 应该是 double 而不是 int:

for (int i=0; i<A.length;i++)
{
    double sum = 0;
    double avg =0;
    for (int j=0; j<A[i].length;j++) {
        sum += A[i][j];
        avg = sum/A[i].length;
    }
    
    System.out.println("The average of the row number: "+(i+1)+" is: "+avg);
}

Answer 2

我认为问题可能出在总和值上，您没有在计算下一行的总和之前删除值。此外我认为平均值可以在打印前循环后计算。

int sum = 0, avg =0;
    for (int i=0; i<A.length;i++)
    {
        sum = 0;

        for (int j=0; j<A[i].length;j++) {
            sum += A[i][j];
        }

        avg = sum/A[i].length;
        
        System.out.println("The average of the row number: "+(i+1)+" is: "+avg);
    }

Answer 3

for (int i=0; i<A.length;i++)
{
    double sum = 0;
    double avg =0;
    for (int j=0; j<A[i].length;j++) {
        sum += A[i][j];
        avg = sum/A[i].length;
    }
    
    System.out.println("The average of the row number: "+(i+1)+" is: "+avg);
}

Answer 4

当然，您也可以使用 lambda 并首先避免此类问题

for(int row = 0; row < A.length; row++) {
  double avg = Arrays.stream(A[row]).boxed().collect(averagingInt(i -> i));
  System.out.println("The average of the row number: " + (row + 1) + " is: " + avg);
}

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