##定义：语句的集合，它们在一起执行一个功能 
###性质
>**·用来完成特定功能的代码片段
·包含于类/对象中
·在程序中被创建，在其他地方被引用
·原子性：一个方法只完成一个功能**（利于后期扩展）

###语法
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy88049d17-ef5d-4601-b68f-e96a065d7c48.jpg)
###程序
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy4fbd2458-a675-4a37-8ce5-9c6345f6a30d.png)
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy827c08cd-f70d-485b-91eb-41d9383fa096.png)

##调用
>**java是值传递**

![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy1562cd4d-bca9-4f74-82c5-5691c4c0dc6d.jpg)
>方法返回值的特例：`return 0;`终止方法
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyab169b98-624d-4064-bb77-d15f44cbdf71.jpg)

##※重载：一个类中，方法名相同，但形式参数不同
>**1.方法名相同
2.参数列表不同（个数or类型or排列顺序...不同）
3.编译器会根据调用方法的参数形式去逐个匹配，从而选择对应的方法**

![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyfd80d77a-d3ac-4046-98f7-e5b8e07e4dbb.jpg)
##命令行传参（了解）
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy8ab79268-9d06-4fb6-bd0b-01178835f84d.png)
用cmd打开程序所在文件夹（Open in→explorer→路径名前＋cmd空格）
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy70f32d27-27a6-49fa-bf55-48d749a09c88.png)

##可变参数：指参数类型后加省略号(...)
>since JDK1.5
**一个方法只能指定一个可变参数，且该参数必须是方法的最后一个参数**
```java
public void test(int... i,int x){} //this is wrong
public void test(int x,int... i){} //this is correct
```

![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudycae30c19-6e66-45a7-955f-1bd241ad4ec6.png)
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy3fc35469-d201-46a1-a89a-fc04d1eb6700.jpg)
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyb0321391-0769-4ca8-9eda-a8d1c558aae7.jpg)

##※递归（思想）：A方法调用A方法（自己调用自己）
>粗暴递归（×）
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyd98f6492-26c2-4846-81a9-903d167a6222.png)

**真·递归——**
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy15ef8ebb-fbb8-476b-92a9-6808a8f11119.png)
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyf68364f9-67c0-4dec-afff-627b4ed38411.jpg)
>能不递归不递归（次数少√次数多×）
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudycf749298-5657-467c-a412-183dc380941f.jpg)

##简易计算器
###读取用户输入+储存
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy31de4a95-0e26-44e8-9c97-80ed930d1efb.png)
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyf07694c5-681c-4746-94f0-268d3bad0ee2.png)
###switch语句的expression
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudyf993b58c-3991-4384-92fa-85a990a4d6e9.png)
###调用方法时的赋值
![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2023/11/06/kuangstudy1f80d0d5-f1a8-4284-99a7-b38ac75df96b.png)
>源码可以直接去问文心一言 写的特别好

TA成长-小游戏demo-java GUI-方法的定义、调用、重载、递归、可变参数、命令行传参、简易计算器

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