什么叫没有类型为Text1的封闭实例

Question

import java.util.Random;

public class Text1 {

    abstract class Pet {
        public abstract void  playSound();
    }
    static class Dog extends Pet{

        @Override
        public void playSound() {
            System.out.println("汪汪....汪");
        }
    }
    static class Cat extends  Pet{

        @Override
        public void playSound() {
            System.out.println("喵喵.....喵");
        }
    }
    static class Sheep extends  Pet{
        @Override
        public void playSound() {
            System.out.println("咩咩.....咩");
        }
    }

    public static void main(String[] args) {

        Random rand=new Random();
        Dog dog=null;
        Cat cat;
        Sheep sheep;
        for(int i=1;i<=5;i++){
            int m=rand.nextInt(3);
            switch(m){
                case 1:
                   dog=new Dog();
                   dog.playSound();
                   break;
                case 2:
                   cat=new Cat();
                   cat.playSound();
                   break;
                case 3:
                   sheep=new Sheep();
                   sheep.playSound();
                   break;

            }
        }
    }
}

import java.util.Random;

public class Text1 {

    abstract class Pet {
        public abstract void  playSound();
    }
    static class Dog extends Pet{

        @Override
        public void playSound() {
            System.out.println("汪汪....汪");
        }
    }
    static class Cat extends  Pet{

        @Override
        public void playSound() {
            System.out.println("喵喵.....喵");
        }
    }
    static class Sheep extends  Pet{
        @Override
        public void playSound() {
            System.out.println("咩咩.....咩");
        }
    }

    public static void main(String[] args) {

        Random rand=new Random();
        Dog dog=null;
        Cat cat;
        Sheep sheep;
        for(int i=1;i<=5;i++){
            int m=rand.nextInt(3);
            switch(m){
                case 1:
                   dog=new Dog();
                   dog.playSound();
                   break;
                case 2:
                   cat=new Cat();
                   cat.playSound();
                   break;
                case 3:
                   sheep=new Sheep();
                   sheep.playSound();
                   break;

            }
        }
    }
}

我是一名刚接触Java的小白，刚学到多态，就是它编译后，就出现标题的，想问一下，这种问题怎么解决

Answer 1

内部类不能定义位抽象类吧，静态内部类是没有问题的