ДЗ Flow

flowcats/src/main/java/otus/homework/flowcats/CatsRepository.kt

@@ -1,17 +1,22 @@
 package otus.homework.flowcats
 
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
 
 class CatsRepository(
     private val catsService: CatsService,
     private val refreshIntervalMs: Long = 5000
 ) {
 
-    fun listenForCatFacts() = flow {
+    fun listenForCatFacts(): Flow<Result<Fact>> = flow {
         while (true) {
-            val latestNews = catsService.getCatFact()
-            emit(latestNews)
+            try {
+                emit(Result.Success(catsService.getCatFact()))
+            } catch (e: Exception) {
+                emit(Result.Error(e))
+                break
+            }
             delay(refreshIntervalMs)
         }
     }

flowcats/src/main/java/otus/homework/flowcats/CatsViewModel.kt

@@ -2,30 +2,41 @@ package otus.homework.flowcats
 
 import androidx.lifecycle.*
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 class CatsViewModel(
     private val catsRepository: CatsRepository
 ) : ViewModel() {
 
-    private val _catsLiveData = MutableLiveData<Fact>()
-    val catsLiveData: LiveData<Fact> = _catsLiveData
+    private val _catsState =
+        MutableStateFlow<Result<Fact>>(Result.Error(IllegalStateException("No data")))
+    val catsState: StateFlow<Result<Fact>> = _catsState.asStateFlow()
 
     init {
         viewModelScope.launch {
-            withContext(Dispatchers.IO) {
-                catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
+            catsRepository.listenForCatFacts()
+                .collect { result ->
+                    _catsState.value = result
                 }
-            }
         }
     }
 }
 
 class CatsViewModelFactory(private val catsRepository: CatsRepository) :
     ViewModelProvider.NewInstanceFactory() {
-    override fun <T : ViewModel?> create(modelClass: Class<T>): T =
+    @Suppress("UNCHECKED_CAST")
+    override fun <T : ViewModel> create(modelClass: Class<T>): T =
         CatsViewModel(catsRepository) as T
-}
+}
+
+sealed class Result<out T> {
+    data class Success<T>(val data: T) : Result<T>()
+    data class Error(val throwable: Throwable) : Result<Nothing>()
+}

flowcats/src/main/java/otus/homework/flowcats/MainActivity.kt

@@ -3,19 +3,39 @@ package otus.homework.flowcats
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import androidx.activity.viewModels
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import kotlinx.coroutines.InternalCoroutinesApi
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+//import androidx.lifecycle.repeatOnLifecycle
 
 class MainActivity : AppCompatActivity() {
 
     private val diContainer = DiContainer()
     private val catsViewModel by viewModels<CatsViewModel> { CatsViewModelFactory(diContainer.repository) }
 
+    @OptIn(InternalCoroutinesApi::class)
     override fun onCreate(savedInstanceState: Bundle?) {
+
         super.onCreate(savedInstanceState)
         val view = layoutInflater.inflate(R.layout.activity_main, null) as CatsView
         setContentView(view)
 
-        catsViewModel.catsLiveData.observe(this){
-            view.populate(it)
+
+        lifecycleScope.launch {
+//            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                catsViewModel.catsState.collect { result ->
+                    when (result) {
+                        is Result.Success -> view.populate(result.data)
+                        is Result.Error -> {
+                            // минимально: лог или заглушка
+                            // Log.e("MainActivity", "Error", result.throwable)
+                        }
+                    }
+                }
+//            }
         }
+
     }
 }

operators/build.gradle

@@ -40,6 +40,7 @@ dependencies {
     implementation 'com.squareup.picasso:picasso:2.71828'
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.3'
     implementation 'androidx.activity:activity-ktx:1.2.3'
+//    implementation "androidx.lifecycle:lifecycle-runtime-ktx"
     testImplementation 'org.jetbrains.kotlinx:kotlinx-coroutines-test:1.4.3'
     implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
 }

operators/src/main/java/otus/homework/flow/SampleInteractor.kt

@@ -1,6 +1,7 @@
 package otus.homework.flow
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.*
 
 @ExperimentalCoroutinesApi
@@ -18,7 +19,12 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .map { it * 5 }
+            .filter { it > 20 }
+            .filter { it % 2 != 0 }
+            .map { "$it won" }
+            .take(3)
     }
 
     /**
@@ -28,8 +34,20 @@ class SampleInteractor(
      * Если входное число делится на 15 - эмитим само число и после него эмитим строку FizzBuzz
      * Если число не делится на 3,5,15 - эмитим само число
      */
+    @OptIn(FlowPreview::class)
     fun task2(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .flatMapConcat { number ->
+                flow {
+                    emit(number.toString())
+
+                    when {
+                        number % 15 == 0 -> emit("FizzBuzz")
+                        number % 3 == 0 -> emit("Fizz")
+                        number % 5 == 0 -> emit("Buzz")
+                    }
+                }
+            }
     }
 
     /**
@@ -38,7 +56,10 @@ class SampleInteractor(
      * Если айтемы в одно из флоу кончились то результирующий флоу также должен закончится
      */
     fun task3(): Flow<Pair<String, String>> {
-        return flowOf()
+        return sampleRepository.produceColors()
+            .zip(sampleRepository.produceForms()) { color, form ->
+                color to form
+            }
     }
 
     /**
@@ -48,6 +69,17 @@ class SampleInteractor(
      * При любом исходе, будь то выброс исключения или успешная отработка функции вызовите метод dotsRepository.completed()
      */
     fun task4(): Flow<Int> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .catch { throwable ->
+                if (throwable is IllegalArgumentException) {
+                    emit(-1)
+                } else {
+                    throw throwable
+                }
+            }
+            .onCompletion {
+                sampleRepository.completed()
+            }
     }
-}
+}
+