一个java的编程题，我是新手，求大神们指导！感谢啊！

我也是初学的，逼自己写的，我也来学习学习...
public class Person
{
public String name;
public int age = 0;
public void setPerson(String name, int age)
{
this.name = name;
this.age = age;
}
public String toString()
{
return "姓名："+name+"\t年龄"+age;
}
}
public class Stud extends Person
{
private int id = 0;//学号
private int fen = 0;//学分
public void setStud(int id,int fen)
{
this.id = id;
this.fen = fen;
}
@Override
public String toString()
{
return "姓名："+name+"\t年龄"+age+"\t学号："+id+"\t学分："+fen;
}

}
public class Test
{
public static void main(String[] args)
{
Person smith = new Person();
Stud james = new Stud();

smith.setPerson("smith", 23);
System.out.println(smith.toString());
james.setPerson("james", 22);
james.setStud(101, 10);
System.out.println(james.toString());
}
}

package test;

public class Person {

private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

class Student extends Person{
private int id;
private int cridt;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getCridt() {
return cridt;
}
public void setCridt(int cridt) {
this.cridt = cridt;
}

public static void main(String[] args) {
Person p = new Person();
Student s = new Student();
p.setName();
p.setAge();
s.setAge();
s.setCridt();
s.setName();
s.setId();

}
}
构造方法没写了.自己加下 ,如果分开在不同的包的话.用import导入下就可以了