使用用户输入创建 2 个二元数组并查找特定列的总和

Question

请协助我的代码。 数组中必须有 3 行和 4 列。 用户必须能够为前 2 列输入双精度。 然后我应该能够计算数组中每列的总和。

public class Main {
public static void main(String[] args) 
{
// Implement scanner
Scanner input = new Scanner(System.in);
// Create loop for accepting matrix input
// Determine row size
System.out.println("Please enter the number 3 for the number of rows in the array:");
int row = input.nextInt();
//Rule for row not being 3
while (row != 3)
{
System.out.println("Sorry, there must be 3 rows.");
row = input.nextInt();
}
// Determine column size
System.out.println("Please enter the number 4 for the number of columns in the array:");
int column = input.nextInt();
//Rule for column not being 4
while (column != 4)
{
System.out.println("Sorry, there must be 4 columns.");
column = input.nextInt();
}
// Declare array with row and columns the user gave
int[][] userArray = new int[row][column];
//Informing user how data is inputted and saved
System.out.print("Note that the following inputs saves the numbers from left to right. So after entering 4 digits it moves onto the next row.");
System.out.println("n");
for(int i=0;i < row ; i++)
{
for(int j=0; j< column; j++)
{ 
System.out.print("Please enter a value for the array:["+i+"]["+j+"]");
int val = input.nextInt();
userArray[i][j] = val;
}
}
printMatrix(userArray, row, column);
}
public static void printMatrix(int[][] array, int row, int column)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
System.out.print(array[i][j] + " ");
}
System.out.println();
}
}
}

打印的输出应为，具体取决于用户输入：

1.9 2.3 5 1

5.0 7.3 6 8

2.4 3.1 3 2

第1列的总和为：9.3

第2列的总和为：12.7

第 3 列的总和为：14

第 4 列的总和为：11

Answer 1

现在需要按列添加数组值。它可以像以下一样简单：

private void printSumForColumn(int[][] array, int col)
{
int sum = 0;
for (int i = 0; i < row; i++)
{
sum += array[i][col];
}
System.out.println("The sum of column " + col + " is " + sum);
}

Answer 2

首先，你不能使用 int 数组来存储浮点数。因此printMatrix方法签名应更改为double[][]。

这是一种计算列和的方法

public static void calColSum(double[][] matrix){
// number of columns
int col = matrix[0].length;
// array to hold column sum
double[] colSums = new double[col];
for (double[] row : matrix) {
for (int y = 0; y < col; y++) {
colSums[y] += row[y];
}
}
for(int x = 0; x< colSums.length; x++){
System.out.println("The sum of column " + x +" is: " + colSums[x]);
}
}