Serialization deserialization of object or POJO (java/ example)

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  • 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.
Serialization and deserialization in java
Fig 1: Serialization of 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

 

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