一个很神奇的问题 为什么会报 Java .lang.InstantiationError 错误呢？

public class findDupicate {

    public static void main(String[] args) {

        animal i1 = new animal();
        cat i2 = new cat();
        

    }

}

class cat {
    public int age = 1;

    public cat() {
        System.out.println("this cat init ");
    }

    public void bark(){
        System.out.println("this is animal");
    }
    
}

class animal {
    public int legNum = 1;

    public animal(){
        System.out.println("this animal init ");
    }

    public void bark(){
        System.out.println("this is animal");
    }
}

输出是这样的

this animal init 
Exception in thread "main" java.lang.InstantiationError: cat
	at findDupicate.main(findDupicate.java:6)
    

为什么 animal 可以实例化成功 而 cat 不行呢？

jdk 版本是 open-jdk 12