Kotlin Serialization Library | Serialization

Introduction

Kotlin Serialization is a Kotlin library that facilitates the serialization and deserialization of Kotlin objects. It provides a way to convert Kotlin data classes into a format that can be easily saved to files, sent over networks, or stored in databases. The library supports various formats, including JSON, ProtoBuf, CBOR, and others. This tutorial will guide you through the installation, configuration, and usage of Kotlin Serialization.

Installation

To use Kotlin Serialization, you need to add the necessary dependencies to your project. For a Gradle project, include the following in your build.gradle.kts file:

                plugins {
                    kotlin("plugin.serialization") version "1.6.0" // Use the latest version
                }

                dependencies {
                    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0") // Use the latest version for JSON
                }

After adding the dependencies, sync your Gradle project to download the necessary libraries.

Basic Usage

Let's create a simple Kotlin data class that we will serialize and deserialize. For example, consider a data class User that holds user information:

                import kotlinx.serialization.Serializable

                @Serializable
                data class User(val name: String, val age: Int)

The @Serializable annotation is essential as it tells the Kotlin Serialization library to process this class.

Serialization

To serialize an instance of the User class into JSON format, use the Json class provided by the library. Here is how you can achieve this:

                import kotlinx.serialization.json.Json

                val user = User("Alice", 25)
                val jsonString = Json.encodeToString(user)
                println(jsonString) // Output: {"name":"Alice","age":25}

Deserialization

Deserialization is the process of converting a JSON string back into a Kotlin object. You can use the Json.decodeFromString method to perform this operation:

                val jsonInput = """{"name":"Bob","age":30}"""
                val userFromJson = Json.decodeFromString(jsonInput)
                println(userFromJson) // Output: User(name=Bob, age=30)

Advanced Features

Kotlin Serialization also supports more advanced features like custom serializers, handling nullable types, and polymorphic serialization. For instance, if you want to customize the serialization behavior of a class, you can create a custom serializer:

                import kotlinx.serialization.KSerializer
                import kotlinx.serialization.Serializer
                import kotlinx.serialization.descriptors.buildClassSerialDescriptor
                import kotlinx.serialization.encoding.Decoder
                import kotlinx.serialization.encoding.Encoder

                @Serializer(forClass = User::class)
                object UserSerializer : KSerializer {
                    override val descriptor = buildClassSerialDescriptor("User")

                    override fun serialize(encoder: Encoder, value: User) {
                        // Custom serialization logic
                    }

                    override fun deserialize(decoder: Decoder): User {
                        // Custom deserialization logic
                        return User("Default", 0)
                    }
                }

This way, you can define exactly how your data class should be processed during serialization and deserialization.

Conclusion

The Kotlin Serialization library provides a powerful and easy-to-use solution for converting Kotlin objects to and from various formats. By following the steps outlined in this tutorial, you should be able to integrate Kotlin Serialization into your projects and take advantage of its features. For more advanced usage and features, refer to the official documentation.

Kotlin Serialization Library Tutorial