practice extends

public class 練習繼承
{
    public static void main(String[] args)
    {
        Undergrad me = new Undergrad();
        Student t1 = me;
        Person t2 = me;
        me.speak();
        me.getCode(20);
        me.getCode();
        System.out.println(me.code);

        t1.speak();
        t1.getCode(40);
        t1.getCode();
        System.out.println(t1.code);

        t2.speak();
        t2.getCode(60);
        t2.getCode();
        System.out.print(t2.code);

    }

}


class Person
{
    public String code = "Person Code";
    protected double getCode(int c)
    {
        System.out.println(code+":"+c);
        return c;
    }
    public void speak()
    {
        System.out.println("I'm a Person!");
    }
}

class Student extends Person
{
    Student()
    {
        System.out.println("I'm a Student!");
    }
    public String code = "Student code";
    public double getCode(int c)
    {
        System.out.println(code+":"+c);
        return c;
    }

    public double getCode()
    {
        System.out.println("Student Code");
        return 0.0;
    }
}

class Undergrad extends Student
{
    public double getCode()
    {
        System.out.println("Student Code");
        return 0.0;
    }

    public void speak()
    {
        System.out.println("I'm an Undergrad!");
    }
}