输入: 输出: import java.util.Scanner; public class Main { public static void main(String[] args) { double[][] str = getArray(); for (int columnIndex = 0; columnIndex < 4; columnIndex++) { System.out.println("Sun of the elements at column" +columnIndex+ " is "+sumColumn(str,columnIndex)); } } public static double[][]getArray(){ double[][] str = new double[3][4]; Scanner input = new Scanner(System.in); System.out.println("Enter a 3-by-4 matrix row bu row:"); for (int i = 0; i < str.length; i++) { for (int j = 0; j < str[i].length; j++) { str[i][j] = input.nextDouble(); } } return str; } public static double sumColumn(double[][] array,int columnIndex){ double sum = 0; for (int i = 0; i < 3; i++) { sum += array[i][columnIndex]; } return sum; } }