JavaOOP

&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 本类&nbsp; &nbsp; &nbsp; &nbsp;同包&nbsp; &nbsp; &nbsp; &nbsp; 子类&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;其他<br>public&nbsp; &nbsp; &nbsp; &nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Y<br>protected&nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Y<br>默认&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br>private&nbsp; &nbsp; &nbsp; Y&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <br>注：Y代表可见&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;

无返回，使用void；有返回值，可以是基本数据类型，引用数据类型，必须有return

无返回，使用void；有返回值，可以是基本数据类型，引用数据类型，必须有return

语法：数据类型&nbsp; &nbsp; 变量名。多个参数使用“，”分隔；

方法定义时的参数列表称为形参；调用方法时，传入的参数称为实参。正确调用方法，参数的类型、个数、顺序需一致

需实例化实现类，再调用方法；

注：不执行的唯一情况，catch块中，System.exit(1)；中断程序，退出java虚拟机

通常用来做资源释放操作：关闭文件，关闭数据库连接等

将函数中可能出现的异常向调用者声明，而自己则不具体处理。

Error类以及他的子类的实例，代表了JVM本身的错误

RuntimeException