abstract class Employee
{
    public String name;
    public abstract double earning();
}

class YearWorker extends Employee
{
     double yearslary;
     YearWorker(){}
    YearWorker(String yourname,double slary)
        {
            name=yourname;
            yearslary=slary;
        }

    public void setslary(double slary)
        {
            yearslary=slary;
        }

    public double earning()
        {
            return yearslary;
        }

    public String toString()
        {
            return String.format("姓名:%s,工资%f",name,yearslary);
        }
}
public class Example
{
    public static void main(String args[])
        {
            Employee a;
            a=new YearWorker("大明",123.45);
           a.name="dongxi";
[color=FF0000]//            a.setslary(150.12);
//        a.yearslary=160.35;[/color]        System.out.println(a.toString());
        }
}
我用的是上转型,为什么注释的这几行他们不能运行啊?谢谢