Flow Homework

flowcats/build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 android {
-    compileSdkVersion 30
+    compileSdkVersion 36
     buildToolsVersion "30.0.3"
 
     namespace = "otus.homework.flowcats"
@@ -47,5 +47,6 @@ dependencies {
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.3'
     implementation 'androidx.activity:activity-ktx:1.2.3'
     testImplementation 'org.jetbrains.kotlinx:kotlinx-coroutines-test:1.4.3'
-    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.6.0'
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.6.0"
 }

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

@@ -1,18 +1,24 @@
 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 {
+                val latestNews = catsService.getCatFact()
+                emit(Result.Success(latestNews))
+            } catch (e: Exception) {
+                Result.Error(e)
+            }
             delay(refreshIntervalMs)
         }
     }
+
 }

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

@@ -3,6 +3,7 @@ package otus.homework.flowcats
 import android.content.Context
 import android.util.AttributeSet
 import android.widget.TextView
+import android.widget.Toast
 import androidx.constraintlayout.widget.ConstraintLayout
 
 class CatsView @JvmOverloads constructor(
@@ -14,9 +15,14 @@ class CatsView @JvmOverloads constructor(
     override fun populate(fact: Fact) {
         findViewById<TextView>(R.id.fact_textView).text = fact.text
     }
+
+    override fun showError(message: String) {
+        Toast.makeText(context, message, Toast.LENGTH_LONG).show()
+    }
 }
 
 interface ICatsView {
 
     fun populate(fact: Fact)
+    fun showError(message: String)
 }

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

@@ -1,31 +1,32 @@
 package otus.homework.flowcats
 
 import androidx.lifecycle.*
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
 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 _catsStateFlow  = MutableStateFlow<Result<Fact>>(Result.Success(Fact()))
+    val catsStateFlow: StateFlow<Result<Fact>> = _catsStateFlow.asStateFlow()
 
     init {
         viewModelScope.launch {
-            withContext(Dispatchers.IO) {
-                catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
-                }
+            catsRepository.listenForCatFacts().collect { result ->
+                _catsStateFlow.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
 }

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

@@ -4,21 +4,21 @@ import com.google.gson.annotations.SerializedName
 
 data class Fact(
 	@field:SerializedName("createdAt")
-	val createdAt: String,
+	val createdAt: String = "",
 	@field:SerializedName("deleted")
-	val deleted: Boolean,
+	val deleted: Boolean = false,
 	@field:SerializedName("_id")
-	val id: String,
+	val id: String = "",
 	@field:SerializedName("text")
-	val text: String,
+	val text: String = "",
 	@field:SerializedName("source")
-	val source: String,
+	val source: String = "",
 	@field:SerializedName("used")
-	val used: Boolean,
+	val used: Boolean = false,
 	@field:SerializedName("type")
-	val type: String,
+	val type: String = "",
 	@field:SerializedName("user")
-	val user: String,
+	val user: String = "",
 	@field:SerializedName("updatedAt")
-	val updatedAt: String
+	val updatedAt: String = ""
 )

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

@@ -3,6 +3,10 @@ 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 androidx.lifecycle.repeatOnLifecycle
+import kotlinx.coroutines.launch
 
 class MainActivity : AppCompatActivity() {
 
@@ -14,8 +18,21 @@ class MainActivity : AppCompatActivity() {
         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.catsStateFlow.collect { result ->
+                    when (result) {
+                        is Result.Success -> {
+                            view.populate(result.data)
+                        }
+                        is Result.Error -> {
+                            view.showError(result.throwable?.message ?: "Unknown error!")
+                        }
+                    }
+                }
+            }
         }
+
+
     }
 }

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

@@ -0,0 +1,6 @@
+package otus.homework.flowcats
+
+sealed class Result<out T> {
+    data class Success<out T>(val data: T) : Result<T>()
+    data class Error(val throwable: Throwable? = null) : Result<Nothing>()
+}

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

@@ -18,7 +18,12 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .map { it * 5 } // 1) умножаем на 5
+            .filter { it > 20 } // 2) убираем числа <= 20
+            .filter { it % 2 != 0 } // 3) убираем четные числа
+            .map { "$it won" } // 4) добавляем постфикс "won"
+            .take(3) // 5) берем 3 первых числа
     }
 
     /**
@@ -29,7 +34,15 @@ class SampleInteractor(
      * Если число не делится на 3,5,15 - эмитим само число
      */
     fun task2(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .flatMapConcat { number ->
+                when {
+                    number % 15 == 0 -> flowOf(number.toString(), "FizzBuzz")
+                    number % 5 == 0 -> flowOf(number.toString(), "Buzz")
+                    number % 3 == 0 -> flowOf(number.toString(), "Fizz")
+                    else -> flowOf(number.toString())
+                }
+            }
     }
 
     /**
@@ -38,7 +51,10 @@ 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 ->
+                Pair(color, form)
+            }
     }
 
     /**
@@ -48,6 +64,16 @@ 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 { e ->
+                if (e is IllegalArgumentException) {
+                    emit(-1)
+                } else {
+                    throw e // пробрасываем другие исключения дальше
+                }
+            }
+            .onCompletion {
+                sampleRepository.completed()
+            }
     }
 }