N*Nのスパイラルマトリクスを印刷

import java.util.Scanner;
public class Test9 {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        while (input.hasNext()) {
            int n = input.nextInt();
            int[][] num = new int[n][n];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    num[i][j] = -1;
                }
            }
            int index = 1;
            int value = 1;
            int i = 0;
            int j = 0;
            int dir = 0; // 0,1,2,3  ， ， ， 

            while (index <= n * n) {
                num[i][j] = value;

                value++;
                switch (dir) {
                case 0:
                    j++;
                    if (j >= n || num[i][j] != -1) {
                        j--;
                        i++;
                        dir = 1;
                    }
                    break;
                case 1:
                    i++;
                    if (i >= n || num[i][j] != -1) {
                        i--;
                        j--;
                        dir = 2;
                    }
                    break;
                case 2:
                    j--;
                    if (j < 0 || num[i][j] != -1) {
                        j++;
                        i--;
                        dir = 3;
                    }
                    break;
                case 3:
                    i--;
                    if (i < 0 || num[i][j] != -1) {
                        i++;
                        j++;
                        dir = 0;
                    }
                    break;
                default:
                    break;
                }
                index++;
            }
            for (i = 0; i < n; i++) {
                for (j = 0; j < n; j++) {
                    if (j == 0) {
                        System.out.print(num[i][j]);
                    } else {
                        System.out.print(" " + num[i][j]);
                    }
                }
                System.out.println();
            }
        }
        input.close();
    }
}