Android Stock App 2: Dagger-Hilt with Multiple Retrofits

8 min readAug 22, 2020

The price of the Stock Exchange is depending on News. On the front page, you shall display the news for the app user. At this time, I choose RapidAPI, which has some free stock APIs. You can choose one as your additional stock news activity. I will divide one activity into three activities:

MainActivity => navigator
TiingoActivity => Tiingo server
BloombergActivity => Bloomberg server

— ===MenU=== —

💲 1. Register A Free Account
💣2. Curl Test
🍨3. RestConfig and Story Data Class
⌘4. Network: Split the API service
🔪5. Split ApiModule: Two Api Services
🐙6. UI: MainActivity, TiingoActivity, and BloombergActivity
📳7. Test Connection and Activities

💲1. Register A Free Account

=> Menu

Top 8 Best Stock Market APIs (for Developers) [2020]

Whether you’re building an algorithmic trading prediction app or charting historical stock market data for various…

rapidapi.com

I choose Bloomberg as my stock news API. It’s free if the requests are less than 500/month or 16/day. That is a great tool for the developer who wants to develop tools on the Stock Exchange.

RapidAPI also offers us some sample programming code. I am working on Android. So Java is the best fit for me.

After registration, we can start to work on the App.

💣2. Curl Test

=> Menu

Open a terminal, such as CMD; let’s use the code from Java.

curl -v "https://bloomberg-market-and-financial-news.p.rapidapi.com/stories/list?template=CURRENCY&id=usdjpy" ^
-H "x-rapidapi-host: bloomberg-market-and-financial-news.p.rapidapi.com" ^
-H "x-rapidapi-key:YOUR API KEY"

It returns a JSON response.

>curl -v ...
*...
<
{...JSON CONTENT...}* Connection #0 to host bloomberg-market-and-financial-news.p.rapidapi.com left intact>

This is a good one.

🍨3. RestConfig and Story Data Class

=> Menu

Add Key and Server

The “secret” will move into the “network” package.

RestConfig.kt: Two sets of API server data: Tiingo and Bloomberg.

class RestConfig {
    companion object {
        const val DEBUG = true
    
        // Tiingo
        const val Tiingo_TEST_END = "/api/test"
        const val Tiingo_TOKEN = "Your Token"
        const val Tiingo_SERVER = "https://api.tiingo.com"
        const val Tiingo_Header1 = "Content-Type: application/json"
        const val Tiingo_Header2 = "Authorization: Token $Tiingo_TOKEN"
    
        // Bloomberg
        const val Bloomberg_STORY_CURRENCY = "/stories/list?template=CURRENCY&id=usdjpy"
        const val Bloomberg_SERVER = "https://bloomberg-market-and-financial-news.p.rapidapi.com"
        const val Bloomberg_KEY = "Your Key"
        const val Bloomberg_Header1 = "x-rapidapi-host: bloomberg-market-and-financial-news.p.rapidapi.com"
        const val Bloomberg_Header2 = "x-rapidapi-key: $Bloomberg_KEY"
    }
}

Split Data Class

At the “data” package, I create a “tiingo” package to store Message class, and I create a “bloomberg” package to store the new data.

JSON:

{"stories":[...}

At data/bloomberg, the response message is “stories”. So I copy the JSON code into JK plugin to generate the Story class.

Story.kt,

data class Story(
    val stories: List<StoryX>,
    val title: String
)

StoryX.kt,

data class StoryX(
    val card: String,
    val internalID: String,
    val longURL: String,
    val primarySite: String,
    val published: Int,
    val resourceType: String,
    val shortURL: String,
    val thumbnailImage: String,
    val title: String
)

We will insert StoryX data on a RecyclerView.

⌘4. Network: Split the API service

=> Menu

I have two API services in my app. So I split them into two packages.

At network/tiingo/:

TiingoApiService.kt,

interface TiingoApiService {
    // Tiingo Test Message
    @Headers(
        RestConfig.Tiingo_Header1,
        RestConfig.Tiingo_Header2
    )
    @GET(RestConfig.Tiingo_TEST_END)
    suspend fun getTestMessage(): Message
}

TiingoApiServiceHelper.kt,

interface TiingoApiServiceHelper {
    suspend fun getTestMsg(): Message
}

TiingoApiServiceHelperImpl.kt

@Singleton
class TiingoApiServiceHelperImpl @Inject constructor(
    private val tiingoApiService: TiingoApiService
) : TiingoApiServiceHelper {
    override suspend fun getTestMsg(): 
        Message = tiingoApiService.getTestMessage()
}

At network/bloomberg:

BloombergApiService.kt,

interface BloombergApiService {
    // Bloomberg Stories: Currency
    @Headers(
        RestConfig.Bloomberg_Header1,
        RestConfig.Bloomberg_Header2
    )
    @GET(RestConfig.Bloomberg_STORY_CURRENCY)
    suspend fun getStory(): Story
}

BloombergApiServiceHelper.kt,

interface BloombergApiServiceHelper {
    // Bloomberg Stories: Currency
    suspend fun getBloombergStory(): Story
}

BloombergApiServiceHelperImpl.kt,

@Singleton
class BloombergApiServiceHelperImpl @Inject constructor(
    private val bloombergApiService: BloombergApiService
) : BloombergApiServiceHelper {
    // Bloomberg Stories: Currency
    override suspend fun getBloombergStory():
        Story = bloombergApiService.getStory()
}

🔪5. Split ApiModule: Two Api Services

=> Menu

I split AppModule into two modules: BloombergNetworkModule and TiingoNetworkModule.

Qualifier: Tag Your Provides

Also, I create two qualifiers to separate the API services. At dagger/qualifier:

TypeEnum.kt, it contains all of the types of API service.

enum class TypeEnum {
    URL, SERVER, GSON, OKHTTP, RETROFIT, APISERVICE, APIHELPER
}

BloombergNetwork.kt,

@Qualifier
@Documented
@Retention(AnnotationRetention.RUNTIME)
annotation class BloombergNetwork(val value: TypeEnum)

TiingoNetwork.kt,

@Qualifier
@Documented
@Retention(AnnotationRetention.RUNTIME)
annotation class TiingoNetwork(val value: TypeEnum)

👩🏻ApiModule: 👶🏻BloombergNetworkModule 👶🏻TiingoNetworkModule

BloombergNetworkModule.kt,

@Module
@InstallIn(ApplicationComponent::class)
class BloombergNetworkModule {
    @Provides @BloombergNetwork(URL)
    fun provideBloombergUrl() = RestConfig.Bloomberg_SERVER    @Provides @BloombergNetwork(GSON)
    fun provideGson(): Gson = GsonBuilder().setLenient().create()    @Provides @BloombergNetwork(OKHTTP)
    fun provideOkHttpClient() =
        if (RestConfig.DEBUG) { // debug ON
            val logger = HttpLoggingInterceptor()
            logger.level = HttpLoggingInterceptor.Level.BODY
            OkHttpClient.Builder()
                .addInterceptor(logger)
                .readTimeout(100, TimeUnit.SECONDS)
                .connectTimeout(100, TimeUnit.SECONDS)
                .build()
        } else // debug OFF
            OkHttpClient.Builder()
                .readTimeout(100, TimeUnit.SECONDS)
                .connectTimeout(100, TimeUnit.SECONDS)
                .build()    @Provides @BloombergNetwork(RETROFIT)
    fun provideRetrofit(
            @BloombergNetwork(OKHTTP) okHttpClient: OkHttpClient,
            @BloombergNetwork(URL) BaseURL: String):
        Retrofit = Retrofit.Builder()
            .baseUrl(BaseURL)
            .client(okHttpClient)
            .addConverterFactory(GsonConverterFactory.create())
            .build()    @Provides @BloombergNetwork(APISERVICE)
    fun provideBloombergApiService(
            @BloombergNetwork(RETROFIT) retrofit: Retrofit):
        BloombergApiService = retrofit.create(BloombergApiService::class.java)    @Provides @BloombergNetwork(APIHELPER)
    fun provideBloomberApiServiceHelper(apiHelper: BloombergApiServiceHelperImpl):
            BloombergApiServiceHelper = apiHelper}

Please check the Bold words, it’s easy to understand qualifier. Let’s tag BloombergApiServiceHelperImpl.kt, at network/bloombBloomberg, to create the binding.

class BloombergApiServiceHelperImpl @Inject constructor(
    @BloombergNetwork(APISERVICE)
    private val bloombergApiService: BloombergApiService
) : BloombergApiServiceHelper {...

Use Hilt anchors to check the binding until you hit the URL tag. Next,

TiingoNetworkModule.kt,

@Module
@InstallIn(ApplicationComponent::class)
class TiingoNetworkModule {
    @Provides @TiingoNetwork(URL)
    fun provideBaseUrl() = RestConfig.Tiingo_SERVER    @Provides @TiingoNetwork(GSON)
    fun provideGson(): Gson = GsonBuilder().setLenient().create()    @Provides @TiingoNetwork(OKHTTP)
    fun provideOkHttpClient() =
        if (RestConfig.DEBUG) { // debug ON
            val logger = HttpLoggingInterceptor()
            logger.level = HttpLoggingInterceptor.Level.BODY
            OkHttpClient.Builder()
                .addInterceptor(logger)
                .readTimeout(100, TimeUnit.SECONDS)
                .connectTimeout(100, TimeUnit.SECONDS)
                .build()
        } else // debug OFF
            OkHttpClient.Builder()
                .readTimeout(100, TimeUnit.SECONDS)
                .connectTimeout(100, TimeUnit.SECONDS)
                .build()    @Provides @TiingoNetwork(RETROFIT)
    fun provideRetrofit(
            @TiingoNetwork(OKHTTP) okHttpClient: OkHttpClient,
            @TiingoNetwork(URL) BaseURL: String
    ): Retrofit = Retrofit.Builder()
            .baseUrl(BaseURL)
            .client(okHttpClient)
            .addConverterFactory(GsonConverterFactory.create())
            .build()    @Provides @TiingoNetwork(APISERVICE)
    fun provideApiService(
            @TiingoNetwork(RETROFIT) retrofit: Retrofit
    ): TiingoApiService = retrofit.create(TiingoApiService::class.java)    @Provides @TiingoNetwork(APIHELPER)
    fun provideApiServiceHelper(apiHelper: TiingoApiServiceHelperImpl):
            TiingoApiServiceHelper = apiHelper}

Let’s fix the TiingoApiServiceHelperImpl.kt, at network/tiingo.

class TiingoApiServiceHelperImpl @Inject constructor(
    @TiingoNetwork(APISERVICE) private val tiingoApiService...

🐙6. UI: MainActivity, TiingoActivity, and BloombergActivity

=> Menu

The MainActivity has no longer to display the Tiingo’s content. Now, it acts as a navigator to show sites that users can visit.

AndroidManifest.xml,

<application
    ...>
    <activity android:name=".view.bloomberg.BloombergNewsActivity"></activity>
    <activity android:name=".view.tiingo.TiingoActivity"></activity>
    <activity android:name=".view.main.MainActivity">

It’s MVVM, so I place all the UI into the “view” package.

MainActivity

The activity_main.xml,

That’s it: two buttons.

MainActivity.kt,

private const val REQUEST_CODE_PERMISSIONS = 1111
private val REQUIRED_PERMISSIONS = arrayOf(...)

@AndroidEntryPoint  // Hilt
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        setupButton()
    }

    fun setupButton() {
        lgd("Setup buttons")
        tiingo_bt.setOnClickListener {
            val mIntent = Intent(this,
                    TiingoActivity::class.java)
            startActivity(mIntent)
        }

        bloomberg_bt.setOnClickListener {
            val mIntent = Intent(this,
                    BloombergNewsActivity::class.java)
            startActivity(mIntent)
        }
    }


    override fun onRequestPermissionsResult(...) {...}

    private fun allPermissionsGranted()...

    companion object {
        private val TAG = "MYLOG MainActivity"
        fun lgd(s: String) = Log.d(TAG, s)
        // len: 0=>short; 1=>long
        fun msg(context: Context, s: String, len: Int) =
            if (len == 0)
                Toast.makeText(context, s,
                    Toast.LENGTH_SHORT).show()
            else
                Toast.makeText(context, s,
                    Toast.LENGTH_LONG).show()

        const val INTERNET = "INTERNET"
    }
}

TiingoActivity

The activity_tiingo.xml,

TiingoActivity.kt, it is as same as old MainActivity. Please rename the ViewModel to TiingoViewModel.

@AndroidEntryPoint  // Hilt
class TiingoActivity : AppCompatActivity() {

    private val tiingoViewModel : TiingoViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_tiingo)

        setupObserver()
    }

    fun setupObserver() {
        lgd("setup observer")
        tiingoViewModel.message.observe(this, Observer {...})
    }

    companion object {
        private val TAG = "MYLOG TiingoAct"
        fun lgd(s: String) = Log.d(TAG, s)
        // len: 0=>short; 1=>long
        fun msg(context: Context, s: String, len: Int) =
                if (len == 0)
                    Toast.makeText(context, s, 
                        Toast.LENGTH_SHORT).show()
                else
                    Toast.makeText(context, s, 
                        Toast.LENGTH_LONG).show()

        const val INTERNET = "INTERNET"
    }
}

TiingoViewModel.kt, it is as same as old MainViewModel. Please rename the Repository to TiingoRepository.

class TiingoViewModel @ViewModelInject constructor(
    private val tiingoRepository: TiingoRepository,
    networkHelper: NetworkHelper
) : ViewModel() {...

TiingoRepository.kt, at the “room” package.

@Singleton
class TiingoRepository @Inject constructor(
    @TiingoNetwork(APIHELPER)
    private val tiingoTiingoApiHelper: TiingoApiServiceHelper
) {
    suspend fun getTestMsg(): 
        Message = tiingoTiingoApiHelper.getTestMsg()
}

Please check the Hilt link. You must be able to jump back to TiingoNetworkModule by clicking 🔨,

BloombergActivity

The activiy_bloomberg_news.html,

BloombergNewsActivity.kt,

@AndroidEntryPoint  // Hilt
class BloombergNewsActivity : AppCompatActivity() {

    private val newsViewModel : BloombergNewsViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_bloomberg_news)

        setupObserver()
    }

    fun setupObserver() {
        newsViewModel.story.observe(this, Observer {
            when (it.status) {
                Status.SUCCESS -> {
                    news_tv.text = it.data!!.stories.toString()
                    news_pb.visibility = View.GONE
                }
                Status.LOADING -> {
                    news_pb.visibility = View.VISIBLE
                }
                Status.ERROR -> {
                    news_pb.visibility = View.GONE

                    val tempStr = it.message

                    // internet error
                    val foundIdx = tempStr?.indexOf(
                        INTERNET, 0)!!
                    if (foundIdx > 0) {
                        val spStr = SpannableString(tempStr)
                        val color = Color.RED
                        spStr.setSpan(
                            ForegroundColorSpan(color),
                            foundIdx,
                            foundIdx+8,
                            Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
                        news_tv.text = spStr
                    } else { // other error
                        news_tv.text = tempStr
                    }
                    msg(this, tempStr, 1)
                }
            }
        })
    }    companion object {
        private val TAG = "MYLOG BloombergAct"
        fun lgd(s: String) = Log.d(TAG, s)
        fun lge(s: String) = Log.e(TAG, s)
        fun lgi(s: String) = Log.i(TAG, s)
        // len: 0=>short; 1=>long
        fun msg(context: Context, s: String, len: Int) =
            if (len == 0)
                Toast.makeText(context, s, 
                        Toast.LENGTH_SHORT).show()
            else
                Toast.makeText(context, s, 
                        Toast.LENGTH_LONG).show()

        const val INTERNET = "INTERNET"
    }
}

BloombergNewsViewModel.kt,

class BloombergNewsViewModel @ViewModelInject constructor(
        private val bloombergRepository: BloombergRepository,
        networkHelper: NetworkHelper
) : ViewModel() {

    // cached
    private val _story = MutableLiveData<Resource<Story>>()
    // public
    val story: LiveData<Resource<Story>> = _story

    init {
        _story.postValue(Resource.loading(null))

        if (networkHelper.isNetworkConnected()) {
            fetchStory()
        } else {
            _story.postValue(
                Resource.error(
                    data = null,
                    message = internetErr))
        }
    }

    fun fetchStory() {
        viewModelScope.launch {
            lgd("fetching story...")
            try {
                _story.value = Resource.success(
                    data = bloombergRepository.getCurrencyStory())
            } catch (exception: Exception) {
                _story.value = Resource.error(
                        data = null,
                        message = exception.message ?: otherErr
                )
            }
        }
    }

    companion object {
        private val TAG = "MYLOG BB-NewsVM"
        const val otherErr = "Error Occurred!"
        const val internetErr = "Internet Connection Error"
        fun lgd(s: String) = Log.d(TAG, s)
    }
}

BloombergRepository.kt, at the “room” package.

@Singleton
class BloombergRepository @Inject constructor(
    @BloombergNetwork(APIHELPER)
    private val bloombergApiHelper: BloombergApiServiceHelper
) {
    suspend fun getCurrencyStory(): 
        Story = bloombergApiHelper.getBloombergStory()
}