7-2 编程练习题答案

import java.util.Scanner;public class Test{public static void main(String[] args){System.out.println("Enter a 4-by-4 matrix row by row: ");Scanner input = new Scanner(System.in);int[][] number = new int[4][4];for(int i = 0; i < number.length; i++)for(int j = 0; j < number[i].length; j++)number[i][j] = input.nextInt();System.out.println("Sum of the elements in the major diagonal is " + sumMajorDiagonal(number));}public static int sumMajorDiagonal(int[][] m){int total = 0;for(int i = 0; i < m.length; i++)total += m[i][i];return total;}}