lecture 11 RxJava3

Author: hoc081098

.editorconfig

@@ -0,0 +1,13 @@
+root = true
+[*]
+indent_size=2
+end_of_line=lf
+charset=utf-8
+trim_trailing_whitespace=true
+insert_final_newline=true
+[*.{kt,kts}]
+ij_kotlin_imports_layout=*
+[*.xml]
+indent_size=4
+[*.java]
+indent_size=4

build.gradle.kts

@@ -15,6 +15,7 @@ repositories {
 dependencies {
     testImplementation(kotlin("test"))
     implementation("org.jetbrains:annotations:24.0.1")
+    implementation("io.reactivex.rxjava3:rxjava:3.1.8")
 }
 
 tasks.test {

src/main/kotlin/Main.kt

@@ -1,7 +1,7 @@
 fun main(args: Array<String>) {
-    println("Hello World!")
+  println("Hello World!")
 
-    // Try adding program arguments via Run/Debug configuration.
-    // Learn more about running applications: https://www.jetbrains.com/help/idea/running-applications.html.
-    println("Program arguments: ${args.joinToString()}")
-}
+  // Try adding program arguments via Run/Debug configuration.
+  // Learn more about running applications: https://www.jetbrains.com/help/idea/running-applications.html.
+  println("Program arguments: ${args.joinToString()}")
+}

src/main/kotlin/com/rxmobileteam/lecture1/Exercise1Main.java

@@ -9,37 +9,37 @@ public static void main(String[] args) {
         ProductService productService = new ProductServiceFactory().createProductService();
 
         Product iPhone12 = new Product(
-                "1",
-                "iPhone 12",
-                "The iPhone 12 and iPhone 12 Mini (stylized as iPhone 12 mini) are smartphones designed, developed, and marketed by Apple Inc. " +
-                        "They are the fourteenth-generation, lower-priced iPhones, succeeding the iPhone 11. " +
-                        "They were unveiled at an Apple Special Event at Apple Park in Cupertino, California on October 13, 2020 " +
-                        "alongside the higher-end iPhone 12 Pro and iPhone 12 Pro Max flagships.",
-                799.99
+            "1",
+            "iPhone 12",
+            "The iPhone 12 and iPhone 12 Mini (stylized as iPhone 12 mini) are smartphones designed, developed, and marketed by Apple Inc. " +
+                "They are the fourteenth-generation, lower-priced iPhones, succeeding the iPhone 11. " +
+                "They were unveiled at an Apple Special Event at Apple Park in Cupertino, California on October 13, 2020 " +
+                "alongside the higher-end iPhone 12 Pro and iPhone 12 Pro Max flagships.",
+            799.99
         );
         Product iPhone12Pro = new Product(
-                "2",
-                "iPhone 12 Pro",
-                "The iPhone 12 Pro and iPhone 12 Pro Max are smartphones designed, developed, and marketed by Apple Inc. " +
-                        "They are the flagship smartphones in the fourteenth-generation iPhone lineup, succeeding the iPhone 11 Pro and iPhone 11 Pro Max, " +
-                        "and were unveiled on October 13, 2020, at Apple Park in Cupertino, California, alongside the lower-end iPhone 12 and iPhone 12 Mini.",
-                999.99
+            "2",
+            "iPhone 12 Pro",
+            "The iPhone 12 Pro and iPhone 12 Pro Max are smartphones designed, developed, and marketed by Apple Inc. " +
+                "They are the flagship smartphones in the fourteenth-generation iPhone lineup, succeeding the iPhone 11 Pro and iPhone 11 Pro Max, " +
+                "and were unveiled on October 13, 2020, at Apple Park in Cupertino, California, alongside the lower-end iPhone 12 and iPhone 12 Mini.",
+            999.99
         );
         Product samsungGalaxyS21 = new Product(
-                "3",
-                "Samsung Galaxy S21",
-                "The Samsung Galaxy S21 is a series of Android-based smartphones designed, developed, marketed, and manufactured by Samsung Electronics as part of its Galaxy S series. " +
-                        "They collectively serve as the successor to the Galaxy S20 series. The S21 series is the first Galaxy S lineup to support the S Pen stylus, " +
-                        "which is only compatible with the Ultra model.",
-                799.99
+            "3",
+            "Samsung Galaxy S21",
+            "The Samsung Galaxy S21 is a series of Android-based smartphones designed, developed, marketed, and manufactured by Samsung Electronics as part of its Galaxy S series. " +
+                "They collectively serve as the successor to the Galaxy S20 series. The S21 series is the first Galaxy S lineup to support the S Pen stylus, " +
+                "which is only compatible with the Ultra model.",
+            799.99
         );
         Product samsungGalaxyS21Ultra = new Product(
-                "4",
-                "Samsung Galaxy S21 Ultra",
-                "The Samsung Galaxy S21 Ultra is a series of Android-based smartphones designed, developed, marketed, and manufactured by Samsung Electronics as part of its Galaxy S series. " +
-                        "They collectively serve as the successor to the Galaxy S20 series. The S21 series is the first Galaxy S lineup to support the S Pen stylus, " +
-                        "which is only compatible with the Ultra model.",
-                1199.99
+            "4",
+            "Samsung Galaxy S21 Ultra",
+            "The Samsung Galaxy S21 Ultra is a series of Android-based smartphones designed, developed, marketed, and manufactured by Samsung Electronics as part of its Galaxy S series. " +
+                "They collectively serve as the successor to the Galaxy S20 series. The S21 series is the first Galaxy S lineup to support the S Pen stylus, " +
+                "which is only compatible with the Ultra model.",
+            1199.99
         );
 
         productService.addProduct(iPhone12);

src/main/kotlin/com/rxmobileteam/lecture1/data/ProductDao.java

@@ -38,4 +38,4 @@ public Set<Product> findAll() {
         throw new ExerciseNotCompletedException();
     }
 
-}
+}

src/main/kotlin/com/rxmobileteam/lecture1/factory/ProductServiceFactory.java

@@ -19,4 +19,4 @@ public ProductService createProductService() {
         // TODO: implement this method
         throw new ExerciseNotCompletedException();
     }
-}
+}

src/main/kotlin/com/rxmobileteam/lecture1/service/Product.java

@@ -12,10 +12,10 @@ public class Product {
     private final double price;
 
     public Product(
-            @NotNull String id,
-            @NotNull String name,
-            @NotNull String description,
-            double price
+        @NotNull String id,
+        @NotNull String name,
+        @NotNull String description,
+        double price
     ) {
         this.id = id;
         this.name = name;
@@ -51,10 +51,10 @@ public int hashCode() {
     @Override
     public String toString() {
         return "Product{" +
-                "id='" + id + '\'' +
-                ", name='" + name + '\'' +
-                ", description='" + description + '\'' +
-                ", price=" + price +
-                '}';
+            "id='" + id + '\'' +
+            ", name='" + name + '\'' +
+            ", description='" + description + '\'' +
+            ", price=" + price +
+            '}';
     }
 }

src/main/kotlin/com/rxmobileteam/lecture1/service/ProductService.java

@@ -35,4 +35,4 @@ public List<Product> searchProducts(String query) {
         // TODO: implement this method
         throw new ExerciseNotCompletedException();
     }
-}
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle1.kt

@@ -0,0 +1,22 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle1 {
+  /**
+   * Transform the given [value] into an Observable that emits the value and then completes.
+   *
+   * Use case: You want to transform some value to the reactive world.
+   */
+  fun solve(value: Int): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}
+
+fun main() {
+  Riddle1.solve(5)
+    .test()
+    .assertResult(5)
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle10.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle10 {
+  /**
+   * Use the [first] Observable and flatten it with the results of the [function] that returns an Observable.
+   *
+   * Use case: Get some user data and perform a network request with the user data and have both data accessible afterwards.
+   */
+  fun solve(first: Observable<Int>, function: (Int) -> Observable<String>): Observable<Pair<Int, String>> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle11.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle11 {
+  /**
+   * Let the first emission of the [source] within a time window of 300ms travel downstream but don't emit any other events until the next time window.
+   *
+   * Use case: Handle the click of a button right away but prevent double clicking by not handling multiple click events within a given time window.
+   */
+  fun solve(source: Observable<Unit>): Observable<Unit> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle12.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle12 {
+  /**
+   * In case the [source] Observable emits an error, don't emit the error and instead complete the Observable with a value of 5.
+   *
+   * Use case: Getting a network error and you want to recover and show some default state.
+   */
+  fun solve(source: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle13.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle13 {
+  /**
+   * When the [source] emits the same value as it did last time, don't allow it to travel downstream.
+   *
+   * Use case: You only want to observe changes of a value but don't care if the same value has been emitted consecutively.
+   */
+  fun solve(source: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle14.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Single
+
+object Riddle14 {
+  /**
+   * Try the given [source] up to three times unless an [IllegalArgumentException] has been emitted.
+   *
+   * Use case: Retry an operation for a number of times or until a valid error occurred.
+   */
+  fun solve(source: Single<Unit>): Single<Unit> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle15.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle15 {
+  /**
+   * Concatenate the [first] Observable with the [second] while subscribing to both early.
+   *
+   * Use case: You have two sources of your data (cache & network request). You want to subscribe to both right away and keep the emission order.
+   */
+  fun solve(first: Observable<Int>, second: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle16.kt

@@ -0,0 +1,18 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+import io.reactivex.rxjava3.core.Single
+
+object Riddle16 {
+  /**
+   * For each emission of the [source] Observable use the [function] and return its value.
+   * Dispose all previously non-terminated returned Singles from the [function] upon receiving a new emission from [source].
+   *
+   * Use case: The [source] Observable is a TextField and you want to issue a network request while disposing the old requests in case the user has typed something new.
+   */
+  fun solve(source: Observable<String>, function: (String) -> Single<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle17.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Single
+
+object Riddle17 {
+  /**
+   * Return a Single that emits the value from the given [function] when being subscribed to.
+   *
+   * Use case: Reactive types are lazy by default. Hence, you might also want to get the value upon the subscription and not execution time.
+   */
+  fun solve(function: () -> Int): Single<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle18.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle18 {
+  /**
+   * Return an Observable that mirrors either the [first] or [second] Observable depending on whoever emits or terminates first.
+   *
+   * Use case: You have multiple sources and want to get the data from either one and then be consistent and not switch between multiple sources.
+   */
+  fun solve(first: Observable<Int>, second: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle19.kt

@@ -0,0 +1,21 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle19 {
+  /**
+   * Use the given [Interaction] interface and use its listener to transform the [Int] callback to an Observable that emits every time the listener is called.
+   * When the Observable is being disposed the listener should be set to null.
+   *
+   * Use case: Transform any listener into an Observable.
+   */
+  fun solve(interaction: Interaction): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+
+  interface Interaction {
+    var listener: ((Int) -> Unit)?
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle2.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle2 {
+  /**
+   * Increment each emitted value of the given [source] by 1.
+   *
+   * Use case: You want to transform the data.
+   */
+  fun solve(source: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}

src/main/kotlin/com/rxmobileteam/lecture11/Riddle20.kt

@@ -0,0 +1,16 @@
+package com.rxmobileteam.lecture11
+
+import com.rxmobileteam.utils.ExerciseNotCompletedException
+import io.reactivex.rxjava3.core.Observable
+
+object Riddle20 {
+  /**
+   * Merge the [first] and [second] Observable together.
+   *
+   * Use case: There something you want to execute and in your UI you have multiple trigger points.
+   */
+  fun solve(first: Observable<Int>, second: Observable<Int>): Observable<Int> {
+    // TODO: implement this method
+    throw ExerciseNotCompletedException()
+  }
+}