ObjectStream Test with hierarchy : ObjectInputStream « File Input Output « Java

ObjectStream Test with hierarchy

   This program is a part of the companion code for Core Java 8th ed.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Date;
import java.util.GregorianCalendar;

 * @version 1.10 17 Aug 1998
 * @author Cay Horstmann
public class ObjectStreamTest
   public static void main(String[] args)
      Employee harry = new Employee("Harry Hacker", 50000, 1989, 10, 1);
      Manager carl = new Manager("Carl Cracker", 80000, 1987, 12, 15);
      Manager tony = new Manager("Tony Tester", 40000, 1990, 3, 15);

      Employee[] staff = new Employee[3];

      staff[0] = carl;
      staff[1] = harry;
      staff[2] = tony;

         // save all employee records to the file employee.dat
         ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("employee.dat"));

         // retrieve all records into a new array
         ObjectInputStream in = new ObjectInputStream(new FileInputStream("employee.dat"));
         Employee[] newStaff = (Employee[]) in.readObject();

         // raise secretary's salary

         // print the newly read employee records
         for (Employee e : newStaff)
      catch (Exception e)

class Employee implements Serializable
   public Employee()

   public Employee(String n, double s, int year, int month, int day)
      name = n;
      salary = s;
      GregorianCalendar calendar = new GregorianCalendar(year, month - 1, day);
      hireDay = calendar.getTime();

   public String getName()
      return name;

   public double getSalary()
      return salary;

   public Date getHireDay()
      return hireDay;

   public void raiseSalary(double byPercent)
      double raise = salary * byPercent / 100;
      salary += raise;

   public String toString()
      return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay
            + "]";

   private String name;
   private double salary;
   private Date hireDay;

class Manager extends Employee
    * Constructs a Manager without a secretary
    * @param n the employee's name
    * @param s the salary
    * @param year the hire year
    * @param month the hire month
    * @param day the hire day
   public Manager(String n, double s, int year, int month, int day)
      super(n, s, year, month, day);
      secretary = null;

    * Assigns a secretary to the manager.
    * @param s the secretary
   public void setSecretary(Employee s)
      secretary = s;

   public String toString()
      return super.toString() + "[secretary=" + secretary + "]";

   private Employee secretary;


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