Clear implementations for branch "coroutines_course_empty"

Author: LukasLechnerDev

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase1/PerformSingleNetworkRequestViewModel.kt

@@ -1,25 +1,13 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase1
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
 import com.lukaslechner.coroutineusecasesonandroid.mock.MockApi
-import kotlinx.coroutines.launch
-import timber.log.Timber
 
 class PerformSingleNetworkRequestViewModel(
     private val mockApi: MockApi = mockApi()
 ) : BaseViewModel<UiState>() {
 
     fun performSingleNetworkRequest() {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
-            try {
-                val recentAndroidVersions = mockApi.getRecentAndroidVersions()
-                uiState.value = UiState.Success(recentAndroidVersions)
-            } catch (exception: Exception) {
-                Timber.e(exception)
-                uiState.value = UiState.Error("Network Request failed!")
-            }
-        }
+
     }
 }

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase10/CalculationInBackgroundViewModel.kt

@@ -1,52 +1,14 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase10
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import java.math.BigInteger
-import kotlin.system.measureTimeMillis
 
 class CalculationInBackgroundViewModel(
     private val defaultDispatcher: CoroutineDispatcher = Dispatchers.Default
 ) : BaseViewModel<UiState>() {
 
     fun performCalculation(factorialOf: Int) {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
-            try {
-                var result: BigInteger = BigInteger.ZERO
-                val computationDuration = measureTimeMillis {
-                    result = calculateFactorialOf(factorialOf)
-                }
 
-                var resultString = ""
-                val stringConversionDuration = measureTimeMillis {
-                    resultString = convertToString(result)
-                }
-
-                uiState.value =
-                    UiState.Success(resultString, computationDuration, stringConversionDuration)
-            } catch (exception: Exception) {
-                UiState.Error("Error while calculating result")
-            }
-        }
     }
-
-    // factorial of n (n!) = 1 * 2 * 3 * 4 * ... * n
-    private suspend fun calculateFactorialOf(number: Int): BigInteger =
-        withContext(defaultDispatcher) {
-            var factorial = BigInteger.ONE
-            for (i in 1..number) {
-                factorial = factorial.multiply(BigInteger.valueOf(i.toLong()))
-            }
-            factorial
-        }
-
-    private suspend fun convertToString(number: BigInteger): String =
-        withContext(defaultDispatcher) {
-            number.toString()
-        }
 }

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase11/CooperativeCancellationViewModel.kt

@@ -3,71 +3,22 @@ package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase1
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
-import kotlinx.coroutines.*
-import java.math.BigInteger
-import kotlin.system.measureTimeMillis
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
 
 class CooperativeCancellationViewModel(
     private val defaultDispatcher: CoroutineDispatcher = Dispatchers.Default
 ) : ViewModel() {
 
-    private var calculationJob: Job? = null
-
     fun performCalculation(factorialOf: Int) {
-        uiState.value = UiState.Loading
-        calculationJob = viewModelScope.launch {
-            try {
-
-                var result: BigInteger = BigInteger.ZERO
-                val computationDuration = measureTimeMillis {
-                    result = calculateFactorialOf(factorialOf)
-                }
-
-                var resultString = ""
-                val stringConversionDuration = measureTimeMillis {
-                    resultString = convertToString(result)
-                }
 
-                uiState.value =
-                    UiState.Success(resultString, computationDuration, stringConversionDuration)
-            } catch (exception: Exception) {
-                uiState.value = if (exception is CancellationException) {
-                    UiState.Error("Calculation was cancelled")
-                } else {
-                    UiState.Error("Error while calculating result")
-                }
-            }
-        }
     }
 
-    // factorial of n (n!) = 1 * 2 * 3 * 4 * ... * n
-    private suspend fun calculateFactorialOf(number: Int): BigInteger =
-        withContext(defaultDispatcher) {
-            var factorial = BigInteger.ONE
-            for (i in 1..number) {
-
-                // yield enables cooperative cancellations
-                // alternatives:
-                // - ensureActive()
-                // - isActive() - possible to do clean up tasks with
-                yield()
-
-                factorial = factorial.multiply(BigInteger.valueOf(i.toLong()))
-            }
-            factorial
-        }
+    fun cancelCalculation() {
 
-    private suspend fun convertToString(number: BigInteger): String =
-        withContext(defaultDispatcher) {
-            number.toString()
-        }
+    }
 
     fun uiState(): LiveData<UiState> = uiState
 
-    fun cancelCalculation() {
-        calculationJob?.cancel()
-    }
-
     private val uiState: MutableLiveData<UiState> = MutableLiveData()
 }

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase12/CalculationInSeveralCoroutinesViewModel.kt

@@ -1,13 +1,8 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase12
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import java.math.BigInteger
-import kotlin.system.measureTimeMillis
 
 class CalculationInSeveralCoroutinesViewModel(
     private val factorialCalculator: FactorialCalculator = FactorialCalculator(),
@@ -18,32 +13,6 @@ class CalculationInSeveralCoroutinesViewModel(
         factorialOf: Int,
         numberOfCoroutines: Int
     ) {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
 
-            var factorialResult = BigInteger.ZERO
-            val computationDuration = measureTimeMillis {
-                factorialResult =
-                    factorialCalculator.calculateFactorial(
-                        factorialOf,
-                        numberOfCoroutines
-                    )
-            }
-
-            var resultString = ""
-            val stringConversionDuration = measureTimeMillis {
-                resultString = convertToString(factorialResult)
-            }
-
-            uiState.value =
-                UiState.Success(resultString, computationDuration, stringConversionDuration)
-        }
     }
-
-    private suspend fun convertToString(
-        number: BigInteger
-    ): String =
-        withContext(defaultDispatcher) {
-            number.toString()
-        }
 }

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase13/ExceptionHandlingViewModel.kt

@@ -1,6 +1,5 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase13
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
 import com.lukaslechner.coroutineusecasesonandroid.mock.MockApi
 import kotlinx.coroutines.*
@@ -11,59 +10,14 @@ class ExceptionHandlingViewModel(
 ) : BaseViewModel<UiState>() {
 
     fun handleExceptionWithTryCatch() {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
-            try {
-                api.getAndroidVersionFeatures(27)
 
-            } catch (exception: Exception) {
-                uiState.value = UiState.Error("Network Request failed: $exception")
-            }
-        }
     }
 
     fun handleWithCoroutineExceptionHandler() {
-        val exceptionHandler = CoroutineExceptionHandler { _, exception ->
-            uiState.value = UiState.Error("Network Request failed!! $exception")
-        }
 
-        uiState.value = UiState.Loading
-        viewModelScope.launch(exceptionHandler) {
-            api.getAndroidVersionFeatures(27)
-        }
     }
 
     fun showResultsEvenIfChildCoroutineFails() {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
 
-            supervisorScope {
-                val oreoFeaturesDeferred = async { api.getAndroidVersionFeatures(27) }
-                val pieFeaturesDeferred = async { api.getAndroidVersionFeatures(28) }
-                val android10FeaturesDeferred = async { api.getAndroidVersionFeatures(29) }
-
-                val versionFeatures = listOf(
-                    oreoFeaturesDeferred,
-                    pieFeaturesDeferred,
-                    android10FeaturesDeferred
-                ).mapNotNull {
-                    try {
-                        it.await()
-                    } catch (exception: Exception) {
-                        // We have to re-throw cancellation exceptions so that
-                        // our Coroutine gets cancelled immediately.
-                        // Otherwise, the CancellationException is ignored
-                        // and the Coroutine keeps running until it reaches the next
-                        // suspension point.
-                        if (exception is CancellationException) {
-                            throw exception
-                        }
-                        Timber.e("Error loading feature data!")
-                        null
-                    }
-                }
-                uiState.value = UiState.Success(versionFeatures)
-            }
-        }
     }
 }

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase14/ContinueCoroutineWhenUserLeavesScreenViewModel.kt

@@ -1,45 +1,17 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase14
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
-import kotlinx.coroutines.launch
 
 class ContinueCoroutineWhenUserLeavesScreenViewModel(
     private var repository: AndroidVersionRepository
 ) : BaseViewModel<UiState>() {
 
-    // more information in this blogpost about "Coroutines & Patterns for work that shouldn't
-    // be cancelled" =>
-    // https://medium.com/androiddevelopers/coroutines-patterns-for-work-that-shouldnt-be-cancelled-e26c40f142ad
-
     fun loadData() {
-        uiState.value = UiState.Loading.LoadFromDb
-
-        viewModelScope.launch {
-            val localVersions = repository.getLocalAndroidVersions()
-            if (localVersions.isNotEmpty()) {
-                uiState.value =
-                    UiState.Success(DataSource.Database, localVersions)
-            } else {
-                uiState.value =
-                    UiState.Error(DataSource.Database, "Database empty!")
-            }
 
-            uiState.value = UiState.Loading.LoadFromNetwork
-
-            try {
-                uiState.value = UiState.Success(
-                    DataSource.Network,
-                    repository.loadAndStoreRemoteAndroidVersions()
-                )
-            } catch (exception: Exception) {
-                uiState.value = UiState.Error(DataSource.Network, "Network Request failed")
-            }
-        }
     }
 
     fun clearDatabase() {
-        repository.clearDatabase()
+
     }
 }
 

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/coroutines/usecase2/Perform2SequentialNetworkRequestsViewModel.kt

@@ -1,28 +1,13 @@
 package com.lukaslechner.coroutineusecasesonandroid.usecases.coroutines.usecase2
 
-import androidx.lifecycle.viewModelScope
 import com.lukaslechner.coroutineusecasesonandroid.base.BaseViewModel
 import com.lukaslechner.coroutineusecasesonandroid.mock.MockApi
-import kotlinx.coroutines.launch
 
 class Perform2SequentialNetworkRequestsViewModel(
     private val mockApi: MockApi = mockApi()
 ) : BaseViewModel<UiState>() {
 
     fun perform2SequentialNetworkRequest() {
-        uiState.value = UiState.Loading
-        viewModelScope.launch {
-            try {
-                val recentVersions = mockApi.getRecentAndroidVersions()
-                val mostRecentVersion = recentVersions.last()
 
-                val featuresOfMostRecentVersion =
-                    mockApi.getAndroidVersionFeatures(mostRecentVersion.apiLevel)
-
-                uiState.value = UiState.Success(featuresOfMostRecentVersion)
-            } catch (exception: Exception) {
-                uiState.value = UiState.Error("Network Request failed")
-            }
-        }
     }
 }