What is serialization in Java?

Table of Contents

• Introduction
• What is Serialization?
  • Key Points about Serialization
• How Serialization Works in Java
  • Steps in Serialization
  • Example of Serialization in Java
    • 1. Creating a Serializable Class
    • 2. Serializing the Object
  • Explanation
• Deserializing the Object
  • Explanation
• Conclusion

Introduction

Serialization in Java is a crucial mechanism that allows the conversion of an object into a byte stream, which can be easily stored in a file or transmitted over a network. This process is vital for object persistence, enabling developers to save the state of an object and retrieve it later. This guide will explain the concept of serialization, how it works, and provide practical examples.

What is Serialization?

Serialization is the process of converting an object into a byte stream, which can then be saved to a disk or sent over a network. This byte stream can later be deserialized back into the original object. The primary purpose of serialization is to facilitate object persistence and communication in distributed applications.

Key Points about Serialization

• Persistence: It allows the state of an object to be saved and restored later.
• Transmission: Serialized objects can be sent over a network, making them useful for remote method invocation (RMI) and web services.
• Platform Independence: Serialized data can be transmitted between different platforms and programming languages, as the byte stream is standardized.

How Serialization Works in Java

To make an object serializable in Java, the class must implement the Serializable interface, which is a marker interface (it has no methods). The Java Virtual Machine (JVM) handles the serialization and deserialization process automatically.

Steps in Serialization

1. Implement Serializable Interface: A class must implement the java.io.Serializable interface.
2. Serialization Process: Use ObjectOutputStream to write the object to a file or output stream.
3. Deserialization Process: Use ObjectInputStream to read the object back from the file or input stream.

Example of Serialization in Java

1. Creating a Serializable Class

Here's an example of a simple class that implements Serializable:

2. Serializing the Object

Next, we'll write code to serialize an instance of the Employee class:

Explanation

• The Employee class implements Serializable, making it eligible for serialization.
• An instance of Employee is created and serialized using ObjectOutputStream, saving it to a file named "employee.ser".

Deserializing the Object

Now, let's deserialize the object back into memory:

Explanation

• The ObjectInputStream reads the serialized object from "employee.ser" and reconstructs it back into an Employee object.
• The object is then printed to the console, showing its state after deserialization.

Conclusion

Serialization in Java is a powerful feature that enables the conversion of objects into byte streams, facilitating their storage and transmission. By implementing the Serializable interface and utilizing ObjectOutputStream and ObjectInputStream, developers can easily manage object persistence and enable communication in distributed applications. Understanding serialization is essential for building robust Java applications that require data storage and transfer capabilities.