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Introduction to GSON in Android

Introduction to GSON in Kotlin Android

GSON is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. GSON provides an easy-to-use API for performing these conversions, making it a popular choice for working with JSON data in Kotlin Android applications.

In this tutorial, we will explore the features of GSON and learn how to install and use it in a Kotlin Android project.

Features of GSON

GSON provides several features that make working with JSON in Kotlin Android applications easier:

  1. Object Serialization: GSON allows you to convert Java objects to JSON representation.

  2. Object Deserialization: GSON can convert a JSON string to an equivalent Java object.

  3. Support for Custom Serialization and Deserialization: GSON provides an API to customize the serialization and deserialization process for specific types.

  4. Support for Generic Types: GSON can handle generic types and correctly serialize and deserialize them.

  5. Support for Collections and Maps: GSON can serialize and deserialize collections and maps, including nested structures.

  6. Configurable Serialization and Deserialization: GSON allows you to configure the serialization and deserialization process by registering custom serializers and deserializers.


To use GSON in your Kotlin Android project, you need to include the GSON library in your project dependencies. Follow these steps to add GSON to your project:

  1. Open your project's build.gradle file.

  2. Add the following line to the dependencies block:

    implementation ''
  3. Sync your project to download the GSON library.


To use GSON in your Kotlin Android application, follow these steps:

  1. Create a new instance of the Gson class:

    val gson = Gson()
  2. Convert an object to JSON string using the toJson method:

    val json = gson.toJson(obj)

    Replace obj with the object you want to convert.

  3. Convert a JSON string to an object using the fromJson method:

    val obj = gson.fromJson(json,

    Replace json with the JSON string and MyClass with the class of the object you want to convert to.

  4. Customize serialization and deserialization using annotations:

    GSON provides several annotations that you can use to customize the serialization and deserialization process. For example, you can use the @SerializedName annotation to specify a different name for a field in the JSON representation.

    data class MyClass(
    @SerializedName("name") val displayName: String,
    val age: Int

    In the example above, the field displayName will be serialized as "name" in the JSON representation.

  5. Register custom serializers and deserializers:

    GSON allows you to register custom serializers and deserializers to handle specific types. To register a custom serializer, implement the JsonSerializer interface. To register a custom deserializer, implement the JsonDeserializer interface. Then, register the serializer or deserializer using the GsonBuilder class:

    val gson = GsonBuilder()
    .registerTypeAdapter(, MySerializer())

    Replace MyClass with the class you want to handle and MySerializer with your custom serializer or deserializer.

These are the basic steps to use GSON in a Kotlin Android application. Refer to the GSON documentation for more advanced usage and features.

GSON How-To Examples