java第五章5.39

好的，你的问题是关于Java第五章的5.39题。这道题目要求你编写一个程序，输入一个整数n，然后输出一个n行n列的矩阵，矩阵中的元素按照从外向内递增的顺序依次填充。

下面是Java代码实现：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[][] matrix = new int[n][n];
        int num = 1;
        int left = 0, right = n - 1, top = 0, bottom = n - 1;
        while (left <= right && top <= bottom) {
            for (int i = left; i <= right; i++) {
                matrix[top][i] = num++;
            }
            for (int i = top + 1; i <= bottom; i++) {
                matrix[i][right] = num++;
            }
            if (left < right && top < bottom) {
                for (int i = right - 1; i >= left; i--) {
                    matrix[bottom][i] = num++;
                }
                for (int i = bottom - 1; i > top; i--) {
                    matrix[i][left] = num++;
                }
            }
            left++;
            right--;
            top++;
            bottom--;
        }
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}