Need Help about Inheritance

java code

class Person
{
   private String name;
 
   public void setName(String n)
   {
      name = n;
   }
 
   public String getName()
   {
      return name;
   }
} 


class Student extends Person
{
   private String stuNum;
 
   public void setStuNum(String sn)
   {
      stuNum = sn;
   }
 
   public String getStuNum()
   {
      return stuNum;
   }
} 


public class TestInheritance
{
   public static void main(String[] args)
   {
      Student stu = new Student();
      stu.setName("John Smith");
      stu.setStuNum("12345");
      System.out.println("Student Name: " + stu.getName());
      System.out.println("Student Number: " + stu.getStuNum());
   }
}

I CAN GET IT RUN ?? pls tell me the solution.
why person class and student class don;t have keyword public ?
This code can be found at

Code:

http://www.learn-programming.za.net/pro ... arn08.html

there must be only one public class and it is the same name of the java file .