homework Flow: Шихов Игорь Борисович

flowcats/build.gradle

@@ -35,17 +35,18 @@ android {
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     implementation 'androidx.core:core-ktx:1.3.2'
+    implementation 'androidx.activity:activity-ktx:1.2.3'
+    implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
+    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
+    implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'com.squareup.retrofit2:retrofit:2.9.0'
     implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
+    implementation 'com.squareup.picasso:picasso:2.71828'
     implementation 'com.google.code.gson:gson:2.8.6'
-    implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'com.google.android.material:material:1.3.0'
-    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
-    implementation 'com.squareup.picasso:picasso:2.71828'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
     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'
 }

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/CatsViewModel.kt

@@ -2,30 +2,54 @@ package otus.homework.flowcats
 
 import androidx.lifecycle.*
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.flow
 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 _catsData = MutableStateFlow<Fact>(value = Unit as Fact)
+    val catsData : StateFlow<Fact> = _catsData
 
-    init {
-        viewModelScope.launch {
-            withContext(Dispatchers.IO) {
+    fun collectFacts() {
+            viewModelScope.launch {
                 catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
+                    _catsData.value = it
                 }
             }
+    }
+
+    fun receiveFacts() : Flow<Result> {
+        return flow {
+            try {
+                catsData.collectLatest() {
+                    it?.also {
+                        emit(Success<Fact>(it))
+                    }
+                }
+            }
+            catch (e: Exception) {
+                emit(Error("Error: " + e.message))
+            }
         }
     }
 }
 
 class CatsViewModelFactory(private val catsRepository: CatsRepository) :
     ViewModelProvider.NewInstanceFactory() {
-    override fun <T : ViewModel?> create(modelClass: Class<T>): T =
+    override fun <T : ViewModel> create(modelClass: Class<T>): T =
         CatsViewModel(catsRepository) as T
-}
+}
+
+sealed class Result()
+
+data class Error(val message : String) : Result()
+
+data class Success<T> (val result : T) : Result()

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

@@ -1,8 +1,16 @@
 package otus.homework.flowcats
 
+import android.app.Activity
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import android.widget.Toast
 import androidx.activity.viewModels
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
 
 class MainActivity : AppCompatActivity() {
 
@@ -14,8 +22,17 @@ class MainActivity : AppCompatActivity() {
         val view = layoutInflater.inflate(R.layout.activity_main, null) as CatsView
         setContentView(view)
 
-        catsViewModel.catsLiveData.observe(this){
-            view.populate(it)
+        catsViewModel.collectFacts()
+
+        catsViewModel.viewModelScope.launch {
+            catsViewModel.receiveFacts().collect() {
+                if (it is Error) {
+                    Toast.makeText(this as Activity, it.message, Toast.LENGTH_LONG).show()
+                }
+                else {
+                    view.populate((it as Success<Fact>).result)
+                }
+            }
         }
     }
 }

operators/src/main/AndroidManifest.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest
     xmlns:android="http://schemas.android.com/apk/res/android"
-    package="otus.homework.flow">
+    package="otus.homework.operators">
 
     <application
         android:allowBackup="true"

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

@@ -18,7 +18,16 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        var count : Int = 0
+        return flow {
+            sampleRepository.produceNumbers().collect() {
+                val n = it * 5
+                if ((n > 20) and ((n % 2) != 0) and (count < 3)) {
+                    emit(n.toString() + " won")
+                    ++count
+                }
+            }
+        }
     }
 
     /**
@@ -29,7 +38,18 @@ class SampleInteractor(
      * Если число не делится на 3,5,15 - эмитим само число
      */
     fun task2(): Flow<String> {
-        return flowOf()
+        return flow {
+            sampleRepository.produceNumbers().collect() {
+                emit(it.toString())
+                if ((it % 15) == 0) {
+                    emit("FizzBuzz")
+                } else if ((it % 5) == 0) {
+                    emit("Buzz")
+                } else if ((it % 3) == 0) {
+                    emit("Fizz")
+                }
+            }
+        }
     }
 
     /**
@@ -38,7 +58,9 @@ class SampleInteractor(
      * Если айтемы в одно из флоу кончились то результирующий флоу также должен закончится
      */
     fun task3(): Flow<Pair<String, String>> {
-        return flowOf()
+        val f1 = sampleRepository.produceColors()
+        val f2 = sampleRepository.produceForms()
+        return f1.zip(f2) { s1, s2 -> Pair(s1, s2) }
     }
 
     /**
@@ -48,6 +70,20 @@ class SampleInteractor(
      * При любом исходе, будь то выброс исключения или успешная отработка функции вызовите метод dotsRepository.completed()
      */
     fun task4(): Flow<Int> {
-        return flowOf()
+        return flow {
+            try {
+                sampleRepository.produceNumbers().collect() {
+                    emit(it)
+                }
+            }
+            catch (e: Throwable) {
+                emit(-1)
+                if (e !is IllegalArgumentException) {
+                    sampleRepository.completed()
+                    throw e
+                }
+            }
+            sampleRepository.completed()
+        }
     }
 }