The first time I run the code fine. However, when i try to run the code again.

Error:

cannot find or load main class Dog;

cause:java.lang.NoClassDefFoundError: dog (wrong name: Dog)

Code:

public interface animal{
    default void greet(animal a){
        System.out.println("Hello,Animal");
    }
    default void sniff(animal a){
        System.out.println("sniff animal");
    }
    default void praise(animal a){
        System.out.println("u r a good animal");
    }
}
public class Dog implements animal{
    @Override
    public void sniff(animal a){
        System.out.println("dog sniff animal");
    }
    void praise(Dog d){
        System.out.println("u r a good dog");
    }
    public static void main(String[] args) {
        Dog d = new Dog();
        animal a=new Dog();
        a.greet(d);
        a.sniff(d);
        d.praise(d);
        a.praise(d);
    }
}

I tried many solutions provided by others, most are useless. One solution that works is that I changed jdk version. But it’s not so useful. When I changed the jdk version , the first run has no problem. The second time I want to run the program, the same error occurs. So I wonder know why this happen when I tried to run the program again.