2023.7.30 周六：内部类

//outer
public class Outer {
    private int id;
    public void out(){
        System.out.println("外部类方法的调用");
    }
   public class inner{
       public void in(){
           System.out.println("内部类方法的调用");
       }
   }
}
//main
public class Main {
    public static void main(String[] args) {
         Outer outer = new Outer();
        Outer.inner inner = outer.new inner();
        inner.in();
    }
}