java 实现二维数组按行列求和

以下是Java代码示例，实现对二维数组按行列求和：

public class SumOf2DArray {
    public static void main(String[] args) {
        int[][] arr = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
        int row = arr.length;
        int col = arr[0].length;
        int[] rowSum = new int[row];
        int[] colSum = new int[col];
        // 按行求和
        for (int i = 0; i < row; i++) {
            int sum = 0;
            for (int j = 0; j < col; j++) {
                sum += arr[i][j];
            }
            rowSum[i] = sum;
        }
        System.out.println("按行求和结果：");
        for (int i = 0; i < row; i++) {
            System.out.print(rowSum[i] + " ");
        }
        System.out.println();
        // 按列求和
        for (int j = 0; j < col; j++) {
            int sum = 0;
            for (int i = 0; i < row; i++) {
                sum += arr[i][j];
            }
            colSum[j] = sum;
        }
        System.out.println("按列求和结果：");
        for (int j = 0; j < col; j++) {
            System.out.print(colSum[j] + " ");
        }
    }
}

输出：

按行求和结果：
6 15 24 
按列求和结果：
12 15 18