// Person: base class adapted from Weiss's book
public class Person { 
   private String name; // name of person 
   private String ssn; // SSN of person 
   private int age; // age of person
   public Person (String n, String s, int a) {
      name = n; ssn = s; age = a;
   }
   public String getName() { return name;}
   public String getSsn() { return ssn;}
   public int getAge() { return age;}
   public String toString() {
      return "Name: " + name + ", SSN: " + ssn + ", Age: " + age;
   }
}

// Employee: class that extends Person
public class Employee extends Person { 
   private double salary;
   public Employee (String n, String ssn, int a, double sal) {
      super(n, ssn, a); salary = sal;
   }
   public double getSalary() { return salary;}
   public String toString() {
      return super.toString() + ", Salary: " + salary;
   }
}

// Student: class that extends Person
public class Student extends Person { 
   private double gpa;
   public Student (String n, String ssn, int a, double g) {
      super(n, ssn, a); gpa = g;
   }
   public double getGpa() { return gpa;}
   public String toString() {
      return super.toString() + ", GPA: " + gpa;
   }
}

// Persons: use the classes Person, Student, and Employee
public class Persons { 
   public static void main(String[] args) {
      Person[] p = new Person[5];
      p[0] = new Person("Williams, John", "534-54-2344", 23);
      p[1] = new Employee("Johnson, Jane", "232-33-3343", 43, 16000.0);
      p[2] = new Student("Wilkins, Jean", "123-89-5688", 19, 3.5);
      p[3] = new Employee("Jacobs, Joe", "112-21-4023", 58, 47000);
      p[4] = new Student("Wilson, James", "003-00-8755", 21, 2.75);

      for (int i = 0; i < p.length; i++)
         System.out.println(p[i]);  
   }
}