Day 21: Parsing JSON in Android Using Kotlin Serialization

🚀 Introduction

Parsing JSON is a fundamental task in Android development, especially when working with APIs. While popular options like Gson and Moshi have served developers well, Kotlin Serialization introduces a Kotlin-first solution that is lightweight, efficient, and multiplatform-friendly.

🔧 What is Kotlin Serialization?

Kotlin Serialization is a powerful library developed by JetBrains that brings native serialization support to Kotlin. It supports formats like JSON, CBOR, and ProtoBuf. It works seamlessly with Kotlin’s type system, making it ideal for Android apps that need fast, safe, and maintainable data parsing.

🛠️ Setup in Android Project

To get started, add the following dependencies to your build.gradle.kts:

kotlinCopyEditplugins {
    kotlin("plugin.serialization") version "1.9.10"
}

dependencies {
    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0")
}

If using Retrofit:

kotlinCopyEditimplementation("com.jakewharton.retrofit:retrofit2-kotlinx-serialization-converter:0.8.0")

🧩 Data Class Example

kotlinCopyEditimport kotlinx.serialization.Serializable

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

📥 Parsing JSON

kotlinCopyEditval json = """{"id":1,"name":"Firoj","email":"firoj@example.com"}"""
val user = Json.decodeFromString<User>(json)

📤 Serializing to JSON

kotlinCopyEditval userJson = Json.encodeToString(user)

🌐 Integration with Retrofit

kotlinCopyEditval retrofit = Retrofit.Builder()
    .baseUrl("https://api.example.com/")
    .addConverterFactory(Json.asConverterFactory("application/json".toMediaType()))
    .build()

⚠️ Error Handling

Kotlin Serialization provides structured exceptions like SerializationException, making it easier to debug issues with mismatched or missing fields.

🆚 Kotlin Serialization vs Gson vs Moshi

✅ When Should You Use Kotlin Serialization?

• If you want faster parsing with lower memory footprint
• If you’re working on Kotlin Multiplatform
• If you want tight integration with Kotlin’s type safety

🔗 Internal Links Suggestions

1. Day 10: Introduction to MVVM in Android – to reference how models are used in MVVM.
2. Day 12: LiveData vs StateFlow – reactive state management with parsed data.
3. Day 20: Connecting to REST APIs with Retrofit – demonstrate integration of Retrofit with Kotlin Serialization.

🧩 Key Points

• Introduction to Kotlin Serialization
• Why choose Kotlin Serialization over Gson or Moshi
• Setup with Gradle and dependencies
• Annotating data classes with @Serializable
• Parsing JSON into Kotlin objects
• Serializing Kotlin objects to JSON
• Integrating with Retrofit
• Error handling and custom serializers

🎯 Conclusion

Kotlin Serialization is a future-proof and modern way to handle JSON in Android. With less boilerplate, better performance, and great integration with Compose, it’s becoming the go-to parser for modern Android development.