java的向上转型

package first;

interface Car {
    void lighting();
}

public class Test implements Car{

    @Override
    public void lighting() {
        // TODO Auto-generated method stub
        
    }

    public void ss(){
        System.out.println("haha");
    }
    
    public static void main(String[] args) {
        Car test = new Test();
        ((Test) test).ss();
    }
}