Java Serialization and Deserialization

Introduction: Serialization is the process of converting an object into a stream of bytes in order to store the object or transmit it to memory, a database, or a file.The reverse process of creating object from binary stream is called deserialization. A Java object is serializable if its class or any of its superclasses implements either the java.io.Serializable interface or its subinterface, java.io.Externalizable.

Serialization classes:

OutputStream : we’ll use FileOutputStream to write data to a file.

ObjectOutputStream : writes primitive data types and graphs of Java objects to an OutputStream.

 WriteObject() Method : it writes an object to the stream.

Deserialization classes:

InputStream : We’ll use FileInputStream as source stream.

ObjectInputStream: It reads from inputStream.

ReadObject() Method:  It reads raw bytes and convert to an object.

In this sample I’ll use a person class and an address class. The person class holds the reference of an address class. We will serialize the data and store it in c:\ project\ folder as tst.ser file. To deserialize the data we will create an instance of FileInputStream class that takes this tst.ser file as source.

Code:

import java.io.Serializable;

public class person implements Serializable {

            String fname;

            String lname;

            int age;

            address addr; //reference class

           

            public person()

            {}

           

            public person(String fn,String ln,int age,address a)

            {

                        this.fname=fn;

                        this.lname=ln;

                        this.age=age;

                        this.addr=a;

            }

           

            public String getFName() {return fname;}

            public String getLName() {return lname;}

            public int getAge() {return age;}

            public address getAddress() { return addr;}

           

            public String setFName(String fn) { return fname=fn;}

            public String setLName(String ln) { return lname=ln;}

            public int setAge(int a) { return age=a;}

            public address setAddress(address adr){return addr=adr;}

           

}

import java.io.Serializable;

public class address implements Serializable{

           

            String str;

            String city;

            String state;

            String zip;

           

            public address(){};

            public address(String a,String c,String s,String z)

            {

                        super();

                        this.str=a;this.city=c;this.state=s;this.zip=z;

            }

   

            public String getStreet(){return str;}

            public String getCity() {return city;}

            public String getState() {return state;}

            public String getZip(){return zip;}

           

            public String setStr(String st){return str=st;}

            public String setCity(String ct){return city=ct;}

            public String setSttae(String st){return state=st;}

            public String setZip(String zp){return zip=zp;}

           

           

}

import java.io.*;

public class serializeDeserailize {

           

            public static void main(String[] args)

            {

                        //create a person instance

                        person p=new person();

                        p.setFName("Adam");

                        p.setLName("Smith");

                        p.setAge(20);

                        //create an address instance

                        address a=new address();

                        a.setStr("Lake Shore Drive");

                        a.setCity("Chicago");

                a.setSttae("IL");

                        a.setZip("65987");

                        p.setAddress(a);

                       

           

                        //Serialize person object

                        try {

                                    FileOutputStream fos=new FileOutputStream("c:/project/tst.ser");

                                    ObjectOutputStream obj=new ObjectOutputStream (fos);

                                    obj.writeObject(p);

                                    obj.close();

                                    fos.close();

                                   

                                   

                           }catch (Exception e)

                        {

                                    e.printStackTrace();

                        }

                       

                        // Deserialize

                       

                        p=null;

                        try {

                                   

                                    InputStream fin=new FileInputStream("c:/project/tst.ser");

                                    ObjectInputStream in=new ObjectInputStream(fin);

                                    p=(person) in.readObject(); //cast to person object

                                    in.close();

                                    fin.close();

                       

                        }catch (Exception ex)

                        {

                                    ex.printStackTrace();

                        }

                       

                        System.out.println("After Deserialization:" );

                        System.out.println("First Name:" + p.getFName());

                        System.out.println("Last Name:" + p.getLName());

                        System.out.println(("Age:" + p.getAge()));

                        System.out.println("Address:" + p.getAddress().getStreet() + " " +  p.getAddress().getCity() + "," +  p.getAddress().getState() + "-" +  p.getAddress().getZip());

                       

            }

            }

Output:

First Name:Adam

Last Name:Smith

Age:20

Address:Lake Shore Drive Chicago,IL-65987