How to use Gson converter with Retrofit in Kotlin Android

How to use Gson converter with Retrofit in Kotlin Android.

Here's a step-by-step tutorial on how to use Gson converter with Retrofit in Kotlin for Android:

1. Start by adding the necessary dependencies to your project. Open your project's build.gradle file and add the following lines inside the dependencies block:

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

2. Create a data class that represents the structure of the JSON response you expect from your API. For example, let's say you have an API endpoint that returns a list of users. You can create a data class like this:

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

3. Next, create an interface that defines your API endpoints. Annotate each endpoint method with appropriate HTTP method annotations (e.g., @GET, @POST, etc.), and specify the expected response type as Call or Observable. For example:

interface ApiService {
    @GET("/users")
    fun getUsers(): Call<List<User>>
}

4. Now, create a Retrofit instance using the Retrofit.Builder class. Configure the base URL of your API and add the Gson converter factory. For example:

val retrofit = Retrofit.Builder()
    .baseUrl("https://api.example.com")
    .addConverterFactory(GsonConverterFactory.create())
    .build()

val apiService = retrofit.create(ApiService::class.java)

5. Finally, make API calls using the generated service instance. For example, to fetch the list of users, you can do:

apiService.getUsers().enqueue(object : Callback<List<User>> {
    override fun onResponse(call: Call<List<User>>, response: Response<List<User>>) {
        if (response.isSuccessful) {
            val users = response.body()
            // Do something with the list of users
        } else {
            // Handle error response
        }
    }

    override fun onFailure(call: Call<List<User>>, t: Throwable) {
        // Handle network failure
    }
})

That's it! You have successfully used Gson converter with Retrofit in Kotlin for Android. Gson will automatically convert the JSON response into a list of User objects for you to use in your app.

Note: Make sure to wrap your API calls in appropriate try-catch blocks and handle any exceptions that may occur during network operations.