👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-04

android retrofit gson coroutines kotlin

I'm prototyping a solution and I'm wondering if anyone has experience with I'm working with a `NullPointerException` when trying to parse the JSON response from a Retrofit API call using Gson in my Android app... The scenario arises intermittently, particularly when the network connection is unstable. Here’s a snippet of the Retrofit service interface: ```kotlin interface ApiService { @GET("/user/profile") suspend fun getUserProfile(): Response<UserProfile> } ``` I've set up my Retrofit client as follows: ```kotlin val retrofit = Retrofit.Builder() .baseUrl("https://api.example.com") .addConverterFactory(GsonConverterFactory.create()) .build() val apiService = retrofit.create(ApiService::class.java) ``` When I call this service from a ViewModel method: ```kotlin viewModelScope.launch { val response = apiService.getUserProfile() if (response.isSuccessful) { val userProfile = response.body() // NullPointerException here // Process userProfile } else { Log.e("API_ERROR", "behavior: ${response.errorBody()?.string()}") } } ``` The `NullPointerException` seems to occur when the JSON response does not contain all expected fields. For instance, if the API returns a response without the `name` field, Gson doesn't instantiate the `UserProfile` object correctly. I've tried making the fields in the `UserProfile` data class nullable, but the exception still occurs. Here’s the `UserProfile` class: ```kotlin data class UserProfile( val id: String, val name: String?, val email: String ) ``` I've also added a try-catch around the code where I call `response.body()` but it doesn't catch the exception thrown. Any insights on how I can handle this better? Is there a configuration in Gson or Retrofit that I might be missing that could prevent this exception from happening? I recently upgraded to Kotlin LTS. I'm using Kotlin 3.10 in this project.