Resource Design Pattern

areadme.md

#Patrón de diseño Resource

• ViewModel
• LiveData
• Observer

Recursos

• Resource.kt: Livedata con canala de distribución
• MyViewModel.kt: Controlador
• MyActivity.kt: actividad principal

MainActivity.kt

class MainActivity : AppCompatActivity() {

    companion object {
        val TAG: String = MainActivity::class.java.simpleName
    }

    private val mViewModel: IpInfoViewModel by lazy {
        ViewModelProviders.of(this).get(IpInfoViewModel::class.java)
    }

    private val changeObserver = Observer<Resource<List<String>>> { value ->
        value?.also {
            when (value.status) {
                Resource.Status.LOADING -> {
                    Log.d(TAG, "Loading...." + value.data)
                }
                Resource.Status.SUCCESS -> {
                    Log.d(TAG, "Success....")
                    Log.d(TAG, value.data.toString())
                }
                Resource.Status.ERROR -> {
                    Log.e(TAG, "Error: ${value.exception?.exceptin}")
                }
            }
        }
    }


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

        mViewModel.mResultData.observe(this, changeObserver)

    }

}

MyViewModel.kt

class MyViewModel(application: Application) : AndroidViewModel(application) {

    val mResultData = MutableLiveData<Resource<List<String>>>()
 
  //for background task
    private var isRunning: Boolean = false
    private val viewModelJob = SupervisorJob()
    private val uiScope = CoroutineScope(Dispatchers.Default + viewModelJob)
  
    override fun onCleared() {
        super.onCleared()
        viewModelJob.cancel()
    }


    fun runSimpleTask() {
        if (!isRunning)
            uiScope.launch {
                Log.d(TAG, "launch DataResponse Load")

                isRunning = true;

                val list = mutableListOf<String>()

                (1..10).forEach {
                    delay(500L)
                    mResultData.postValue(Resource.loading(listOf("${Thread.currentThread().name} generate steep:$it")))
                    list.add("Name $it")
                }

                //mResultData.postValue(Resource.error(AppException(e)))
                mResultData.postValue(Resource.success(list))
                isRunning = false
            }
    }


    companion object {
        val TAG: String = IpInfoViewModel::class.java.simpleName
    }

}

Resource.kt

class Resource<T> private constructor(val status: Status, val data: T?, val exception: AppException?) {
    enum class Status {
        SUCCESS, ERROR, LOADING
    }
    companion object {
        fun <T> success(data: T?): Resource<T> {
            return Resource(
                Status.SUCCESS,
                data,
                null
            )
        }
        fun <T> error(exception: AppException?): Resource<T> {
            return Resource(
                Status.ERROR,
                null,
                exception
            )
        }
        fun <T> loading(data: T?): Resource<T> {
            return Resource(
                Status.LOADING,
                data,
                null
            )
        }
    }
}