What is Serialization and Deserialization in Java?

Serialization and Deserialization are mechanisms in Java used to convert objects into a transferable or storable format and then rebuild them back into objects.

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🔹 Serialization

Serialization is the process of converting a Java object into a byte stream so it can be:

• Stored in a file

• Sent across a network

• Cached or saved in databases

👉 Object → Byte Stream

Example

import java.io.*;

class Student implements Serializable {
    int id;
    String name;

    Student(int id, String name) {
        this.id = id;
        this.name = name;
    }
}

public class SerializeDemo {
    public static void main(String[] args) throws Exception {
        Student s1 = new Student(101, "Rahul");

        FileOutputStream fileOut = new FileOutputStream("student.ser");
        ObjectOutputStream out = new ObjectOutputStream(fileOut);

        out.writeObject(s1); // Serialization
        out.close();
    }
}

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🔹 Deserialization

Deserialization is the reverse process where the byte stream is converted back into the original Java object.

👉 Byte Stream → Object

Example

import java.io.*;

public class DeserializeDemo {
    public static void main(String[] args) throws Exception {
        FileInputStream fileIn = new FileInputStream("student.ser");
        ObjectInputStream in = new ObjectInputStream(fileIn);

        Student s2 = (Student) in.readObject(); // Deserialization
        in.close();

        System.out.println(s2.name);
    }
}

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🔹 Important Points

• Class must implement Serializable interface.

• Serializable is a marker interface (no methods).

• transient keyword prevents fields from being serialized.

• Commonly used in distributed systems, APIs, and session management.

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🔹 Key Differences

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