Value JSON Serialization Demo

This project demonstrates the serialization and deserialization of immutable value objects using the Gson library. The implementation focuses on correctly handling immutable objects without requiring modifications or annotations in their source code. It includes a custom adapter to manage the serialization and deserialization of a generic class, ensuring that parameterised types are interpreted accurately, such as correctly distinguishing between integers and doubles within these objects.

Overview

The project showcases:

• Polymorphic serialization and deserialization using Gson.
• A custom type adapter to prevent integers from being interpreted as doubles when dealing with generic types.

Serialization/Deserialization Example Use Case

To illustrate the functionality, the application creates several shape objects (a circle, cylinders with different content types, and a rectangle), serializes them into JSON format, and then deserializes them back into their original shape objects.

1. Original shapes:

   Original shapes:
   Circle[radius=4.2]
   Cylinder[radius=4.4, height=2.2, content=Some content]
   Cylinder[radius=12.3, height=3.4, content=42]
   Cylinder[radius=18.9, height=5.2, content=42.24]
   Rectangle[a=10, b=20]
   

2. Serialized shapes:

   Serialized shapes:
   {"shapeType":"com.github.ahauschulte.demo.valueserialization.Circle","radius":4.2}
   {"shapeType":"com.github.ahauschulte.demo.valueserialization.Cylinder","radius":4.4,"height":2.2,"paramType":"java.lang.String","content":"Some content"}
   {"shapeType":"com.github.ahauschulte.demo.valueserialization.Cylinder","radius":12.3,"height":3.4,"paramType":"java.lang.Integer","content":42}
   {"shapeType":"com.github.ahauschulte.demo.valueserialization.Cylinder","radius":18.9,"height":5.2,"paramType":"java.lang.Double","content":42.24}
   {"shapeType":"com.github.ahauschulte.demo.valueserialization.Rectangle","a":10,"b":20}
   

3. Deserialized shapes:

   Deserialized shapes:
   Circle[radius=4.2]
   Cylinder[radius=4.4, height=2.2, content=Some content]
   Cylinder[radius=12.3, height=3.4, content=42]
   Cylinder[radius=18.9, height=5.2, content=42.24]
   Rectangle[a=10, b=20]
   

Project Structure

• Main.java: The entry point of the application. It creates shape instances, serializes them to JSON, and deserializes them back to shape objects.
• Shape.java: A sealed interface that all shape types (Circle, Cylinder, Rectangle) implement.
• Circle.java: A record representing a circle with a radius.
• Rectangle.java: A record representing a rectangle with width and height.
• Cylinder.java: A record representing a cylinder with a radius, height, and generic content.
• CylinderTypeAdapter.java: A custom type adapter for serializing and deserializing Cylinder objects.

Getting Started

Prerequisites

Ensure you have the following installed:

• Java 21 or higher
• Maven

Building the Project

1. Clone the repository:

   git clone https://github.com/ahauschulte/value-json-serialization.git
   cd value-json-serialization

2. Build the project using Maven:

   mvn clean package

Running the Application

Run the Main class to see the serialization and deserialization in action:

mvn exec:java -Dexec.mainClass="com.github.ahauschulte.demo.valueserialization.Main"

Code Explanation

Main.java

The Main class demonstrates the core functionality:

• Shape Type Registration: Registers the shape types for polymorphic serialization using RuntimeTypeAdapterFactory.
• Gson Configuration: Configures Gson with the custom CylinderTypeAdapter and the RuntimeTypeAdapterFactory.
• Shape Creation: Creates instances of Circle, Cylinder (with string, integer, and double content), and Rectangle.
• Serialization: Serializes the shape objects to JSON.
• Deserialization: Deserializes the JSON strings back to shape objects.

CylinderTypeAdapter.java

A custom type adapter to handle the serialization and deserialization of Cylinder objects with generic content:

• Serialization: Adds the type of the content along with the content itself to the JSON representation.
• Deserialization: Uses the content type to correctly deserialize the content element, preventing type mismatches.

AI Tools Used

This project utilises AI tools, specifically ChatGPT by OpenAI, to assist with documentation and provide guidance on the effective use of the Gson library. All AI-generated content has been reviewed and validated by human contributors to ensure accuracy and quality.