日期:2014-05-20 浏览次数:20652 次
class Person { String name; int age; public void say() { System.out.println("I am fater"); } public void work() { System.out.println("I hava a job"); } } class Child extends Person { public void say() { System.out.println("I am child"); } public void dance() {System.out.print("I can dance");} }
public static void main(String[] args) { // TODO Auto-generated method stub Person per=new Child(); per.say(); per.work(); Child ch=(Child)per; ch.dance(); ch.say(); //为什么下面会报错呢? Child ch1=(Child)new Person(); }