I just add new Mouse() after Object obj =, but it still didn't work.
package zh.codegym.task.task14.task1406;
/*
没有错误
*/
public class Solution {
public static void main(String[] args) {
Object obj = new Mouse();// 在此添加代码
Mouse mouse = (Mouse) obj;
GrayMouse grayMouse = (GrayMouse) mouse;
Jerry jerry = (Jerry) grayMouse;
printClasses(obj, mouse, grayMouse, jerry);
}
public static void printClasses(Object obj, Mouse mouse, GrayMouse grayMouse, Jerry jerry) {
System.out.println(jerry.getClass().getSimpleName());
System.out.println(grayMouse.getClass().getSimpleName());
System.out.println(mouse.getClass().getSimpleName());
System.out.println(obj.getClass().getSimpleName());
}
static class Mouse {
}
static class GrayMouse extends Mouse {
}
static class Jerry extends GrayMouse {
}
}