Serialization deserialization of object or POJO (java/ example)

• Serialization is the process of saving the objects loaded in the memory to corresponding streams
  • e.g Saving the objects to file system.
• Deserialization is the process of loading the saved data to corresponding objects.
• We have already discussed about the basics of serialization and deserialization process.

What Serializable interface?

•  Serializable is a marker interface.
  • Serializable interface does not contain any method.
• Serializable interface is used to inform the JVM that class wants serialization feature.

public interface Serializable {
}

Serialize the object or pojo in java using Serializable interface

1.) Person class or POJO class:

• We would like to serialize the Person class.
  • The person class should implement the Serializable interface.
• We will use following classes for Serialization & Deserialization:
  • ObjectOutputStream will be used to serialize person object.
  • ObjectInputStream will be used to deserialize person object.

import java.io.Serializable;

public class Person implements Serializable {

 private static final long serialVersionUID = 1L;
 public String firstName;
 public String lastName;
 public int age;
 public String contact;
 public Person(String firstName, String lastName,
    int age, String contact) {
  this.firstName = firstName;
  this.lastName = lastName;
  this.age = age;
  this.contact = contact;
 }
 public String toString() {
     return "[" + firstName + " " + lastName +
         " " + age + " " +contact +"]";
 }
}

2.) SerializeDeserialize class:

We have written couple of methods to serialize and deserialize person objects.

1. serialize method : serialize method will save person object to “savePerson.txt” file.
   • serialize method will prints the serialized person object.
2. deserialize method: deserialize method will deserialize person object saved in savePerson.txt file
   • deserialize method, prints the deserialized person object.

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class SerializeDeserialize {

 public static void serialize() throws IOException {
  Person person = new Person("Mike", "harvey", 34, "001894536");
  FileOutputStream output = new FileOutputStream(new File("savePerson.txt"));
  ObjectOutputStream outputStream = new ObjectOutputStream(output);
  outputStream.writeObject(person);
  output.close();
  outputStream.close();
  System.out.println("Serialized the person object : "+person);
 } 
 public static void deSerialize() throws IOException, ClassNotFoundException {
  
  FileInputStream inputStream = new FileInputStream(new File("savePerson.txt"));
  ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
  Person person = (Person) objectInputStream.readObject();
  System.out.println("Deserialize the person object :"+ person);
                objectInputStream.close();
  inputStream.close();
 }
 
 public static void main(String[] args) throws IOException, ClassNotFoundException {
  serialize();
  deSerialize();
 }
}

Output – Serialize & deserialize person object or POJO in java

Serialized the person object : [Mike harvey 34 001894536]
Deserialize the person object :[Mike harvey 34 001894536]

Download code – Serialization & deserialization object in java