无法理解递归 [英] Trouble Understanding Recursion

问题描述

好的，我有一个程序:

public class Rec {
    public static void main(String[] args) {
        test(5);
    }
    static void test(int n) {
        if (n > 0) {
        System.out.println(n);
        test(n-1);
        System.out.println(n);
        }
    }

它的输出是 5,4,3,2,1,1,2,3,4,5.我的问题是，为什么/如何执行第二个 println(n) 语句?我认为函数调用会完全切断它，相反它的行为让我感到困惑.这不是家庭作业或其他任何东西，我真的很难理解递归的工作原理.

It's output is 5,4,3,2,1,1,2,3,4,5. My question is, why/how does the second println(n) statement get executed? I thought that the function call would completely cut it off, instead it acted in a way that baffles me. This isn't homework or anything, I just really am having a hard time understanding how recursion works.

推荐答案

所有方法调用完成后都返回同一个地方.

All method calls return to the same place once they are done.

通过有效地将它们链接起来

By effectively chaining them you get

 System.out.println(5)
     System.out.println(4)
        System.out.println(3)
            System.out.println(2)
                system.out.println(1)
                   // If is not true now.
                System.out.println(1)
            System.out.println(2)
        System.out.println(3)
     System.out.println(4)
 System.out.println(5)

有意义吗?

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