java中的数组2-D

Question

我想写一个java程序，打印二维数组每行的平均值，但它只适用于第一行。我不知道问题出在哪里。

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

每次循环时都需要将sum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。此外，avg和sum应该是双精度，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sum值上，您不能在计算下一行的sum之前删除值。此外，我认为在打印之前可以在循环之后计算平均值。

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并从一开始就避免这样的问题

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);
}