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;
	}
}