Pavel Iokhin Flow fxed

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

@@ -1,7 +1,9 @@
 package otus.homework.flowcats
 
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOn
 
 class CatsRepository(
     private val catsService: CatsService,
@@ -14,5 +16,5 @@ class CatsRepository(
             emit(latestNews)
             delay(refreshIntervalMs)
         }
-    }
+    }.flowOn(Dispatchers.IO)
 }

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

@@ -2,6 +2,8 @@ package otus.homework.flowcats
 
 import android.content.Context
 import android.util.AttributeSet
+import android.view.View
+import android.widget.ProgressBar
 import android.widget.TextView
 import androidx.constraintlayout.widget.ConstraintLayout
 
@@ -14,9 +16,18 @@ class CatsView @JvmOverloads constructor(
     override fun populate(fact: Fact) {
         findViewById<TextView>(R.id.fact_textView).text = fact.text
     }
+
+    override fun setLoadingVisible(visible: Boolean) {
+        findViewById<ProgressBar>(R.id.loading).visibility = if (visible) {
+            View.VISIBLE
+        } else {
+            View.GONE
+        }
+    }
 }
 
 interface ICatsView {
 
     fun populate(fact: Fact)
+    fun setLoadingVisible(visible: Boolean)
 }

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

@@ -1,27 +1,21 @@
 package otus.homework.flowcats
 
 import androidx.lifecycle.*
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
+import kotlinx.coroutines.flow.*
 
 class CatsViewModel(
     private val catsRepository: CatsRepository
 ) : ViewModel() {
-
-    private val _catsLiveData = MutableLiveData<Fact>()
-    val catsLiveData: LiveData<Fact> = _catsLiveData
-
-    init {
-        viewModelScope.launch {
-            withContext(Dispatchers.IO) {
-                catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
-                }
-            }
+    val catsState = catsRepository.listenForCatFacts()
+        .map { Result.Success(it) }
+        .catch<Result<Fact>> {
+            emit(Result.Error(it))
         }
-    }
+        .stateIn(
+            viewModelScope,
+            SharingStarted.WhileSubscribed(5000),
+            Result.Loading
+        )
 }
 
 class CatsViewModelFactory(private val catsRepository: CatsRepository) :

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

@@ -2,7 +2,11 @@ package otus.homework.flowcats
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import android.widget.Toast
 import androidx.activity.viewModels
+import androidx.lifecycle.lifecycleScope
+import kotlinx.coroutines.flow.collect
+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 {
+            catsViewModel.catsState.collect {
+                when (it) {
+                    is Result.Success -> {
+                        view.setLoadingVisible(false)
+                        view.populate(it.data)
+                    }
+                    is Result.Error -> Toast.makeText(
+                        this@MainActivity,
+                        it.exception.message,
+                        Toast.LENGTH_SHORT
+                    ).show()
+                    is Result.Loading -> view.setLoadingVisible(true)
+                }
+            }
         }
     }
 }

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

@@ -0,0 +1,7 @@
+package otus.homework.flowcats
+
+sealed class Result<out T : Any> {
+    data class Success<out T : Any>(val data: T) : Result<T>()
+    data class Error(val exception: Throwable) : Result<Nothing>()
+    object Loading : Result<Nothing>()
+}

flowcats/src/main/res/layout/activity_main.xml

@@ -18,4 +18,15 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <ProgressBar
+        android:id="@+id/loading"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:visibility="gone"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        />
+
 </otus.homework.flowcats.CatsView>

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

@@ -18,7 +18,11 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .map { it * 5 }
+            .filter { it > 20 && it % 2 == 1 }
+            .take(3)
+            .map { "$it won" }
     }
 
     /**
@@ -29,7 +33,17 @@ class SampleInteractor(
      * Если число не делится на 3,5,15 - эмитим само число
      */
     fun task2(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .transform {
+                emit("$it")
+                if (it % 15 == 0) {
+                    emit("FizzBuzz")
+                } else if (it % 5 == 0) {
+                    emit("Buzz")
+                } else if (it % 3 == 0) {
+                    emit("Fizz")
+                }
+            }
     }
 
     /**
@@ -38,7 +52,10 @@ 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()) { f1, f2 ->
+                Pair(f1, f2)
+            }
     }
 
     /**
@@ -48,6 +65,13 @@ 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 {
+                when (it) {
+                    is java.lang.IllegalArgumentException -> emit(-1)
+                    else -> throw it
+                }
+            }
+            .onCompletion { sampleRepository.completed() }
     }
 }