java教程题目，斐波那契数列算兔子的程序求大神解释代码意思

[牛忧果]

import java.util.Scanner; public class demo { public static void main(String[] args) { System.out.println("请输入月数："); Scanner scanner = new Scanner(System.in); int n = scanner.nextInt(); int m = run(n-1) + run(n-2); //递推公式 System.out.println("第"+ n + "个月有" + m + "对兔子"); scanner.close(); } public static int run(int n) { //递归方法 if(n==1||n==2) return 1; else return run(n-1)+run(n-2); //递归调用 } }