Java内部类

package com.oop.demo10;

public class Outer {

    private int id = 10;
    public void out(){
        System.out.println("这是外部类的方法");
    }

    public class Inner{
        public void in(){
            System.out.println("这是内部类的方法");
        }

        //获得外部类的私有属性
        public void getID(){
            System.out.println(id);
        }
    }

}

package com.oop;

import com.oop.demo10.Outer;

public class Application {
    public static void main(String[] args) {
        //new
        Outer outer = new Outer();
        //通过这个外部类来实例化内部类
        Outer.Inner inner = outer.new Inner();
        inner.getID();

    }
}

---

package com.oop.demo10;

public class Outer {

}

//一个java类中可以有多个 class 类，但是只能有一个 public class
class A{
    public static void main(String[] args) {

    }
}

---

package com.oop.demo10;

public class Outer {

    //局部内部类
    public void method(){
        class Inner{
            public void in(){
                
            }
        }
    }

}

---

package com.oop.demo10;

//思维、操作

public class Test {
    public static void main(String[] args) {
        //没有名字初始化类，不用将实例保存到变量中
        new Apple().eat();

        //匿名内部类
        new UserSevice(){
            @Override
            public void hello() {

            }
        };
    }
}

class Apple{
    public void eat(){
        System.out.println("1");
    }
}

interface UserSevice{
    void hello();
}