Add FlatMap Transformation Example

Author: LEMUBIT

src/main/java/TransformingObservables/FlatMap.java

@@ -0,0 +1,68 @@
+/*
+* transform the items emitted by an Observable into Observables, then flatten the emissions from those into a single Observable
+*
+* The FlatMap operator transforms an Observable by applying a function that you specify to each item emitted by the source Observable,
+* where that function returns an Observable that itself emits items. FlatMap then merges the emissions of these resulting Observables,
+* emitting these merged results as its own sequence.
+  This method is useful, for example, when you have an Observable that emits a series of items that themselves have Observable members or
+  are in other ways transformable into Observables, so that you can create a new Observable that emits the complete collection of items
+  emitted by the sub-Observables of these items.
+  Note that FlatMap merges the emissions of these Observables, so that they may interleave.
+* */
+
+package TransformingObservables;
+
+import rx.Observable;
+
+public class FlatMap {
+    public static void main(String[] args) {
+        Observable.just(1, 2, 3)
+                .flatMap(integer -> Observable.just("A", "B", "C").map(integer1 -> integer + integer1))
+                .subscribe(
+                        integer -> System.out.println(integer),
+                        throwable -> System.out.println("Error"),
+                        () -> System.out.println("Complete")
+                );
+
+
+        System.out.println("---------------------");
+        Observable.just(1, 2, 3)
+                .flatMap(integer -> addOne(integer))
+                .flatMap(integer -> multiplyByTwo(integer))
+                .subscribe(integer -> System.out.println(integer),
+                        throwable -> System.out.println("Error"),
+                        () -> System.out.println("Completed")
+                );
+    }
+
+
+    //needs to return Observable
+    public static Observable<Integer> addOne(int x) {
+        return Observable.just(x + 1);
+    }
+
+
+    public static Observable<Integer> multiplyByTwo(int x) {
+        return Observable.just(x * 2);
+    }
+}
+
+
+/*
+* OUTPUT:
+1A
+1B
+1C
+2A
+2B
+2C
+3A
+3B
+3C
+Complete
+---------------------
+4
+6
+8
+Completed
+* */

src/main/java/TransformingObservables/GroupBy.java

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+package TransformingObservables;
+
+import rx.Observable;
+import rx.functions.Func1;
+
+public class GroupBy {
+    public static void main(String[] args) {
+//        Observable.just(1,2,3).groupBy(integer -> integer%2)
+//                .flatMap(booleanIntegerGroupedObservable ->booleanIntegerGroupedObservable.subscribeOn(s->System.out.println(s)) );
+
+    }
+}