Integrate Retrofit with Jetpack Compose for robust network operations.
Retrofit API Interface
Define suspend functions for async operations:
interface UserApi {
@GET("users/{id}")
suspend fun getUser(@Path("id") userId: String): User
@POST("users")
suspend fun createUser(@Body user: User): User
@DELETE("users/{id}")
suspend fun deleteUser(@Path("id") userId: String)
}
Retrofit Builder with OkHttp
Configure Retrofit with interceptors:
val okHttpClient = OkHttpClient.Builder()
.addInterceptor { chain ->
val request = chain.request()
.newBuilder()
.addHeader("Authorization", "Bearer $token")
.build()
chain.proceed(request)
}
.addInterceptor(HttpLoggingInterceptor().setLevel(BODY))
.build()
val retrofit = Retrofit.Builder()
.baseUrl("https://api.example.com/")
.client(okHttpClient)
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(UserApi::class.java)
Safe API Call Error Handling
Wrap API calls with error handling:
suspend inline fun <T> safeApiCall(
crossinline apiCall: suspend () -> T
): Result<T> = try {
Result.success(apiCall())
} catch (e: HttpException) {
when (e.code()) {
404 -> Result.failure(Exception("Not found"))
401 -> Result.failure(Exception("Unauthorized"))
else -> Result.failure(e)
}
} catch (e: Exception) {
Result.failure(e)
}
ViewModel with Compose State
Integrate API calls into ViewModel:
@HiltViewModel
class UserViewModel @Inject constructor(
private val userApi: UserApi
) : ViewModel() {
private val _uiState = MutableStateFlow<UiState>(UiState.Loading)
val uiState: StateFlow<UiState> = _uiState
fun loadUser(userId: String) {
viewModelScope.launch {
_uiState.value = UiState.Loading
_uiState.value = safeApiCall {
userApi.getUser(userId)
}.fold(
onSuccess = { UiState.Success(it) },
onFailure = { UiState.Error(it.message ?: "Unknown error") }
)
}
}
}
HttpException Code Mapping
Handle specific HTTP status codes:
sealed class ApiError(message: String) : Exception(message) {
object NotFound : ApiError("Resource not found")
object Unauthorized : ApiError("Authentication required")
object ServerError : ApiError("Server error")
class Unknown(msg: String) : ApiError(msg)
}
fun HttpException.toApiError(): ApiError = when (code()) {
404 -> ApiError.NotFound
401 -> ApiError.Unauthorized
in 500..599 -> ApiError.ServerError
else -> ApiError.Unknown(message())
}
Build reliable, type-safe API integration with Retrofit and Compose.
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