内部类

Outer.Inner oi = new Outer().new Inner();
oi.method();

class Outer{
    private int num = 10;
    private class Inner{
        int a = 1;
        public void method() {
            System.out.println(num);
        }
    }
    public void print() {
        Inner i= new Inner();
        i.method();
    }
    
}

public class demon3 {
    public static void main(String[] args) {
        Out.In o1 = new Out.In(); 
        o1.methon();
        Out.In.print();
    }     
}
class Out{
    static class In{
        public void methon() {
            System.out.println("Out.In.methon()");
        }
        public static void print() {
            System.out.println("Out.In.print()");
        }
    }
}

public class demon4 {
    public static void main(String[] args) {    
        wai.nei wn = new wai().new nei();
        wn.show();
    }
}
class wai{
    int num = 10;
    public class nei{
        int num = 20;
        public void show() {
            int num = 30;
            System.out.println(num);             //   30  谁最近用谁
            System.out.println(this.num);　　　　 //   20
            System.out.println(wai.this.num);　　//   10
        }
    }
}