Introduction

• In Java, serialization and deserialization is a key concept used frequently in real-world applications, even though we may not always realize it.
• Serialization:
  • It is the process of converting an object into a byte stream so that it can be easily stored in files, memory or databases or transmitted over a network.
  • In Java, serialization is done using the ObjectOutputStream class.
• Deserialization:
  • It is the reverse process of serialization. It involves converting the byte stream back into an object.
  • In Java, deserialization is done using the ObjectInputStream class.
• Diagram:

Advantages of Serialization:

1. Object Persistence:
   • Serialization allows objects to be saved to files or databases, enabling the persistence of their state.
2. Data Transfer:
   • It helps in sending objects over a network by converting them into a byte stream that can be easily transmitted.
3. Cross-Platform Compatibility:
   • Serialized objects can be transferred between different platforms or systems without compatibility issues since the byte stream format is platform-independent.
4. Caching:
   • Serialization helps in storing objects in memory or on disk for efficient access, reducing redundant calculations or database queries.
5. Backup and Restore:
   • Serialized objects can be backed up in a file and restored later, ensuring that the state of an application is preserved.

Advantages of Deserialization:

1. Reconstruction of Objects:
   • Deserialization enables the recreation of objects from byte streams, restoring their original state and allowing continued use.
2. Data Retrieval:
   • It allows objects to be retrieved from a file, memory, or database, enabling an application to resume its state after a restart or network transfer.
3. Cross-Platform Compatibility:
   • Just like serialization, deserialization ensures that objects can be read and used across different platforms, making the system more flexible.
4. Session Management:
   • Helps in restoring user sessions by deserializing session data that was serialized earlier, providing a seamless experience.

Serialization & Deserialization Program:

• We have one Student class, we will create an object of Student class and serialize and deserialize it.

  import java.io.Serializable;
  
  public class Student implements Serializable
  {
      // Define the instance variables
      private String name;
      private int rollno;
  
      // Constructor to initialize the variables
      public Student(String name, int rollno)
      {
          this.name = name;
          this.rollno = rollno;
      }
  
      // Getters for the variables
      public String getName() {
          return name;
      }
  
      public int getRollno() {
          return rollno;
      }
  
      // Displaying student details
      public void display()
      {
          System.out.println("Name: " + name);
          System.out.println("Roll No: " + rollno);
      }
  }

• Now we will serialize Student class object using ObjectOutputStream class as follows:

  import java.io.FileOutputStream;
  import java.io.ObjectOutputStream;
  import java.io.IOException;
  
  public class SerializationExample
  {
      public static void main(String[] args)
      {
          // Create a Student object
          Student student = new Student("Deepak", 101);
  
          // Serialize the object
          try (
                  FileOutputStream fileOut = new FileOutputStream("student.ser");
                  ObjectOutputStream out = new ObjectOutputStream(fileOut)
              )
          {
              out.writeObject(student);  // Serialize the student object
              System.out.println("Student object has been serialized.");
          }
          catch (IOException e)
          {
              e.printStackTrace();
          }
      }
  }

  Output:

  Student object has been serialized.

• Now, we will deserialize Student object using ObjectInputStream class as follows:

  import java.io.FileInputStream;
  import java.io.ObjectInputStream;
  import java.io.IOException;
  
  public class DeserializationExample
  {
      public static void main(String[] args)
      {
          // Deserialize the object
          try (
                  FileInputStream fileIn = new FileInputStream("student.ser");
                  ObjectInputStream in = new ObjectInputStream(fileIn)
              )
          {
              Student student = (Student) in.readObject();  // Deserialize the object
              System.out.println("Student object has been deserialized.");
              student.display();  // Display the student details
          }
          catch (IOException | ClassNotFoundException e)
          {
              e.printStackTrace();
          }
      }
  }

  Output:

  Student object has been deserialized.
  Name: Deepak
  Roll No: 101