任意阶空心三角形。java版。

import java.util.Scanner;
public class KongTa {
    public static void main(String []args){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入层数：");
        int n = sc.nextInt();
        for(int i = 1;i <= n;i++){
            for(int k = 1;k <= n-i;k++){
                System.out.print(" ");
            }
            for(int j = 1;j <= 2 * i - 1;j++){
                if(j == 1||j == 2 * i - 1||i == n) {
                    System.out.print("*");
                }
                else {
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
    }
}