Operator: forEach

language-adaptors/rxjava-groovy/src/test/groovy/rx/lang/groovy/ObservableTests.groovy

@@ -22,6 +22,7 @@ import java.util.Arrays;
 
 import org.junit.Before;
 import org.junit.Test;
+import static org.junit.Assert.*;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
@@ -213,6 +214,44 @@ def class ObservableTests {
         Observable.toSortedList(Observable.toObservable(1, 3, 2, 5, 4), {a, b -> a - b}).subscribe({ result -> a.received(result)});
         verify(a, times(1)).received(Arrays.asList(1, 2, 3, 4, 5));
     }
+
+    @Test
+    public void testForEach() {
+        Observable.create(new AsyncObservable()).forEach({ result -> a.received(result)});
+        verify(a, times(1)).received(1);
+        verify(a, times(1)).received(2);
+        verify(a, times(1)).received(3);
+    }
+
+    @Test
+    public void testForEachWithError() {
+        try {
+            Observable.create(new AsyncObservable()).forEach({ result -> throw new RuntimeException('err')});
+            fail("we expect an exception to be thrown");
+        }catch(Exception e) {
+            // do nothing as we expect this
+        }
+    }
+
+    def class AsyncObservable implements Func1<Observer<Integer>, Subscription> {
+
+        public Subscription call(final Observer<Integer> observer) {
+            new Thread(new Runnable() {
+                public void run() {
+                    try {
+                        Thread.sleep(50)
+                    }catch(Exception e) {
+                        // ignore
+                    }
+                    observer.onNext(1);
+                    observer.onNext(2);
+                    observer.onNext(3);
+                    observer.onCompleted();
+                }
+            }).start();
+            return Observable.noOpSubscription();
+        }
+    }
 
     def class TestFactory {
         int counter = 1;

rxjava-core/src/main/java/rx/Observable.java

@@ -22,9 +22,11 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -332,6 +334,84 @@ public void onNext(T args) {
         });
     }
 
+    /**
+     * Invokes an action for each element in the observable sequence, and blocks until the sequence is terminated.
+     * <p>
+     * NOTE: This will block even if the Observable is asynchronous.
+     * <p>
+     * This is similar to {@link #subscribe(Observer)} but blocks. Because it blocks it does not need the {@link Observer#onCompleted()} or {@link Observer#onError(Exception)} methods.
+     * 
+     * @param onNext
+     *            {@link Action1}
+     * @throws RuntimeException
+     *             if error occurs
+     */
+    public void forEach(final Action1<T> onNext) {
+        final CountDownLatch latch = new CountDownLatch(1);
+        final AtomicReference<Exception> exceptionFromOnError = new AtomicReference<Exception>();
+
+        subscribe(new Observer<T>() {
+            public void onCompleted() {
+                latch.countDown();
+            }
+
+            public void onError(Exception e) {
+                /*
+                 * If we receive an onError event we set the reference on the outer thread
+                 * so we can git it and throw after the latch.await().
+                 * 
+                 * We do this instead of throwing directly since this may be on a different thread and the latch is still waiting.
+                 */
+                exceptionFromOnError.set(e);
+                latch.countDown();
+            }
+
+            public void onNext(T args) {
+                onNext.call(args);
+            }
+        });
+        // block until the subscription completes and then return
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            // set the interrupted flag again so callers can still get it
+            // for more information see https://github.com/Netflix/RxJava/pull/147#issuecomment-13624780
+            Thread.currentThread().interrupt();
+            // using Runtime so it is not checked
+            throw new RuntimeException("Interrupted while waiting for subscription to complete.", e);
+        }
+
+        if (exceptionFromOnError.get() != null) {
+            if (exceptionFromOnError.get() instanceof RuntimeException) {
+                throw (RuntimeException) exceptionFromOnError.get();
+            } else {
+                throw new RuntimeException(exceptionFromOnError.get());
+            }
+        }
+    }
+
+    @SuppressWarnings({ "rawtypes", "unchecked" })
+    public void forEach(final Object o) {
+        if (o instanceof Action1) {
+            // in case a dynamic language is not correctly handling the overloaded methods and we receive an Action1 just forward to the correct method.
+            forEach((Action1) o);
+        }
+
+        // lookup and memoize onNext
+        if (o == null) {
+            throw new RuntimeException("onNext must be implemented");
+        }
+        final FuncN onNext = Functions.from(o);
+
+        forEach(new Action1() {
+
+            public void call(Object args) {
+                onNext.call(args);
+            }
+
+        });
+    }
+
     /**
      * Allow the {@link RxJavaErrorHandler} to receive the exception from onError.
      * 
@@ -2543,7 +2623,6 @@ public void testSequenceEqual() {
             verify(result, times(1)).onNext(false);
         }
 
-
-
     }
+
 }

rxjava-core/src/main/java/rx/util/AtomicObserver.java

@@ -67,8 +67,13 @@ public void onError(Exception e) {
 
     @Override
     public void onNext(T args) {
-        if (!isFinished.get()) {
-            actual.onNext(args);
+        try {
+            if (!isFinished.get()) {
+                actual.onNext(args);
+            }
+        }catch(Exception e) {
+            // handle errors if the onNext implementation fails, not just if the Observable fails
+            onError(e);
         }
     }