completablefuture whencomplete vs thenapply

Why is the article "the" used in "He invented THE slide rule"? Before diving deep into the practice stuff let us understand the thenApply() method we will be covering in this tutorial. Find the method declaration of thenApply from Java doc. thenApply/thenApplyAsync, and their counterparts thenCompose/thenComposeAsync, handle/handleAsync, thenAccept/thenAcceptAsync, are all asynchronous! Returns a new CompletableFuture that is completed when this CompletableFuture completes, with the result of the given function of the exception triggering this CompletableFuture's completion when it completes exceptionally; otherwise, if this CompletableFuture completes normally, then the returned CompletableFuture also completes normally with the same value. thenCompose() is better for chaining CompletableFuture. If no exception is thrown then only the normal action will be performed. This method is analogous to Optional.flatMap and Can a private person deceive a defendant to obtain evidence? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, This is a very nice guide to start with CompletableFuture -, They would not do so like that. How can I recognize one? However after few days of playing with it I. But when the thenApply stage is cancelled, the completionFuture still may get completed when the pollRemoteServer(jobId).equals("COMPLETE") condition is fulfilled, as that polling doesnt stop. In this tutorial, we will explore the Java 8 CompletableFuture thenApply method. Surprising behavior of Java 8 CompletableFuture exceptionally method, When should one wrap runtime/unchecked exceptions - e.g. Drift correction for sensor readings using a high-pass filter. When there is an exception from doSomethingThatMightThrowAnException, are both doSomethingElse and handleException run, or is the exception consumed by either the whenComplete or the exceptionally? The function supplied to thenApply may run on any of the threads that, while the 2 overloads of thenApplyAsync either. but I give you another way to throw a checked exception in CompletableFuture. (Any assumption of order is implementation dependent.). This is a similar idea to Javascript's Promise. The take away is that for thenApply, the runtime promises to eventually run your function using some executor which you do not control. The following example is, through the results of the first step, go to two different places to calculate, whoever returns sooner, you can see the difference between them. Not the answer you're looking for? Can I pass an array as arguments to a method with variable arguments in Java? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The end result being, Javascript's Promise.then is implemented in two parts - thenApply and thenCompose - in Java. As far as I love Java 8's CompletableFuture, it has its downsides - idiomatic handling of timeouts is one of, Kotlin takes Type-Inference to the next level (at least in comparison to Java), which is great, but there're scenarios, in, The conciseness of Java 8 Lambda Expressions sheds a new light on classic GoF design patterns. rev2023.3.1.43266. This method is analogous to Optional.flatMap and Launching the CI/CD and R Collectives and community editing features for How can I pad an integer with zeros on the left? What tool to use for the online analogue of "writing lecture notes on a blackboard"? Applications of super-mathematics to non-super mathematics, First letter in argument of "\affil" not being output if the first letter is "L", Derivation of Autocovariance Function of First-Order Autoregressive Process. 1.2 CompletableFuture . completion of its result. So, thenApplyAsync has to wait for the previous thenApplyAsync's result: In your case you first do the synchronous work and then the asynchronous one. CompletableFuture public interface CompletionStage<T> A stage of a possibly asynchronous computation, that performs an action or computes a value when another CompletionStage completes. The take away is they promise to run it somewhere eventually, under something you do not control. CompletableFuture<String> cf2 = cf1.thenApply(s -> s + " from the Future!"); There are three "then-apply" methods. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? @Holger: Why not use get() method? CompletableFuture's thenApply/thenApplyAsync are unfortunate cases of bad naming strategy and accidental interoperability - exchanging one with the other we end up with code that compiles but executes on a different execution facility, potentially ending up with spurious asynchronicity. Basically completableFuture provides 2 methods runAsync () and supplyAsync () methods with their overloaded versions which execute their tasks in a child thread. Each operator on CompletableFuture generally has 3 versions. Follow. Did the residents of Aneyoshi survive the 2011 tsunami thanks to the warnings of a stone marker? When that stage completes normally, the Thus thenApply and thenCompose have to be distinctly named, or Java compiler would complain about identical method signatures. Find centralized, trusted content and collaborate around the technologies you use most. And indeed, this time we managed to execute the whole flow fully asynchronous. Supply a Function to each call, whose result will be the input to the next Function. Other than quotes and umlaut, does " mean anything special? Can a private person deceive a defendant to obtain evidence? For those looking for other ways on exception handling with completableFuture. Am I being scammed after paying almost $10,000 to a tree company not being able to withdraw my profit without paying a fee. value. CompletableFuture.thenApply () method is inherited from the CompletionStage thenApply and thenCompose both return a CompletableFuture as their own result. As you can see, theres no mention about the shared ForkJoinPool but only a reference to the default asynchronous execution facility which turns out to be the one provided by CompletableFuture#defaultExecutor method, which can be either a common ForkJoinPool or a mysterious ThreadPerTaskExecutor which simply spins up a new thread for each task which sounds like an controversial idea: Luckily, we can supply our Executor instance to the thenApplyAsync method: And finally, we managed to regain full control over our asynchronous processing flow and execute it on a thread pool of our choice. Propagating the exception via completeExceptionally. Could someone provide an example in which case I have to use thenApply and when thenCompose? What is the difference between public, protected, package-private and private in Java? extends U> fn and Function> fn are considered the same Runtime type - Function. Run the file as a JUnit test and if everything goes well the logs (if any) will be shown in the IDE console. How did Dominion legally obtain text messages from Fox News hosts? If you compile your code against the OpenJDK libraries, the answer is in the, Whether "call 2" executes on the main thread or some other thread is dependant on the state of. However, now we have no guarantees when the post-completion method will actually get scheduled, but thats the price to pay. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If this is your class you should know if it does throw, if not check docs for libraries that you use. Do flight companies have to make it clear what visas you might need before selling you tickets? Can a VGA monitor be connected to parallel port? However, you might be surprised by the fact that subsequent stages will receive the exception of a previous stage wrapped within a CompletionException, as discussed here, so its not exactly the same exception: Note that you can always append multiple actions on one stage instead of chaining then: Of course, since now there is no dependency between the stage 2a and 2b, there is no ordering between them and in the case of async action, they may run concurrently. Why was the nose gear of Concorde located so far aft? But the computation may also be executed asynchronously by the thread that completes the future or some other thread that calls a method on the same CompletableFuture. Flutter change focus color and icon color but not works. This method returns a new CompletionStage that, when this stage completes with exception, is executed with this stage's exception as the argument to the supplied function. Could someone provide an example in which case I have to use thenApply and when thenCompose? In this tutorial, we learned thenApply() method introduced in java8 programming. Currently I'm working at Luminis(Full stack engineer) on a project in a squad where we use Java 8, Cucumber, Lombok, Spring, Jenkins, Sonar and more. By leveraging functional programming, Principal Engineer at Mi|iM, ex-Lead Architect at HazelcastFollow @pivovarit. PTIJ Should we be afraid of Artificial Intelligence? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The article's conclusion does not apply because you mis-quoted it. Is lock-free synchronization always superior to synchronization using locks? Implementations of CompletionStage may provide means of achieving such effects, as appropriate. 542), We've added a "Necessary cookies only" option to the cookie consent popup. Connect and share knowledge within a single location that is structured and easy to search. I only write it up in my mind. private void test1() throws ExecutionException, InterruptedException {. Why did the Soviets not shoot down US spy satellites during the Cold War? value as the CompletionStage returned by the given function. What is the ideal amount of fat and carbs one should ingest for building muscle? It is correct and more concise. thenApply () - Returns a new CompletionStage where the type of the result is based on the argument to the supplied function of thenApply () method. Vivek Naskar. Catch looks like this: Throwables.throwIfUnchecked(e.getCause()); throw new RuntimeException(e.getCause()); @Holger excellent answer! You can read my other answer if you are also confused about a related function thenApplyAsync. The difference is in the return types: thenCompose() works like Scala's flatMap which flattens nested futures. Use them when you intend to do something to CompletableFuture's result with a Function. Let me try to explain the difference between thenApply and thenCompose with an example. Why catch and rethrow an exception in C#? Level Up Coding. Connect and share knowledge within a single location that is structured and easy to search. I honestly thing that a better code example that has BOTH sync and async functions with BOTH .supplyAsync().thenApply() and .supplyAsync(). and I prefer your first one that you used in this question. In which thread do CompletableFuture's completion handlers execute? Thanks for contributing an answer to Stack Overflow! December 2nd, 2021 How to convert Character to String and a String to Character Array in Java, java.io.FileNotFoundException How to solve File Not Found Exception, java.lang.arrayindexoutofboundsexception How to handle Array Index Out Of Bounds Exception, java.lang.NoClassDefFoundError How to solve No Class Def Found Error, The method is represented by the syntax CompletionStage thenApply(Function fn), The method is used to perform some extra task on the result of another task. But we don't know the relationship of jobId = schedule (something) and pollRemoteServer (jobId). . Does With(NoLock) help with query performance? rev2023.3.1.43266. CompletableFuture in Java 8 is a huge step forward. thenApply (fn) - runs fn on a thread defined by the CompleteableFuture on which it is called, so you generally cannot know where this will be executed. supplied function. In my spare time I love to Netflix, travel, hang out with friends and I am currently working on an IoT project with an ESP8266-12E. I have the following code (resulting from my previous question) that schedules a task on a remote server, and then polls for completion using ScheduledExecutorService#scheduleAtFixedRate. Learn how your comment data is processed. CompletableFuture . exceptional completion. Was Galileo expecting to see so many stars? The Function you supplied sometimes needs to do something synchronously. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Use them when you intend to do something to CompletableFuture's result with a Function. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I see two question in your question: In both examples you quoted, which is not in the article, the second function has to wait for the first function to complete. Then Joe C's answer is not misleading. JCGs (Java Code Geeks) is an independent online community focused on creating the ultimate Java to Java developers resource center; targeted at the technical architect, technical team lead (senior developer), project manager and junior developers alike. It might immediately execute if the result is already available. When we re-throw the cause of the CompletionException, we may face unchecked exceptions, i.e. Retracting Acceptance Offer to Graduate School. When that stage completes normally, the Why do we kill some animals but not others? I get that the 2nd argument of thenCompose extends the CompletionStage where thenApply does not. 3.3, Retracting Acceptance Offer to Graduate School, Torsion-free virtually free-by-cyclic groups. But pay attention to the last log, the callback was executed on the common ForkJoinPool, argh! a.thenApply(b); a.thenApply(c); means a finishes, then b or c can start, in any order. So when you cancel the thenApply future, the original completionFuture object remains unaffected as it doesnt depend on the thenApply stage. To learn more, see our tips on writing great answers. Asking for help, clarification, or responding to other answers. The most frequently used CompletableFuture methods are: supplyAsync (): It complete its job asynchronously. The result of supplier is run by a task from ForkJoinPool.commonPool() as default. This way, once the preceding function has been executed, its thread is now free to execute thenApply. This means both function can start once receiver completes, in an unspecified order. using a Function with thenApply: Chaining CompletableFuture s effectively is equivalent to attaching callbacks to the event "my future completed". This solution got me going. Here the output will be 2. We can also pass . thenCompose( s -> callSync (() -> s), null); with the callSync -method being: Code (Java): Meaning of a quantum field given by an operator-valued distribution. super T,? one that returns a CompletableFuture). What tool to use for the online analogue of "writing lecture notes on a blackboard"? Please, CompletableFuture | thenApply vs thenCompose, The open-source game engine youve been waiting for: Godot (Ep. Not the answer you're looking for? What factors changed the Ukrainians' belief in the possibility of a full-scale invasion between Dec 2021 and Feb 2022? supplied function. Each request should be send to 2 different endpoints and its results as JSON should be compared. Regarding your last question, which future is the one I should hold on to?, there is no requirement to have a linear chain of futures, in fact, while the convenience methods of CompletableFuture make it easy to create such a chain, more than often, its the least useful thing to do, as you could just write a block of code, if you have a linear dependency. 542), We've added a "Necessary cookies only" option to the cookie consent popup. 3.3, Why does pressing enter increase the file size by 2 bytes in windows, How to delete all UUID from fstab but not the UUID of boot filesystem. This method is analogous to Optional.map and Stream.map. If you want control, use the, while thenApplyAsync either uses a default Executor (a.k.a. CompletableFuture is a feature for asynchronous programming using Java. You can chain multiple thenApply or thenCompose together. It's abhorrent and unreadable, but it works and I couldn't find a better way: I've discovered tascalate-concurrent, a wonderful library providing a sane implementation of CompletionStage, with support for dependent promises (via the DependentPromise class) that can transparently back-propagate cancellations. Critical issues have been reported with the following SDK versions: com.google.android.gms:play-services-safetynet:17.0.0, Flutter Dart - get localized country name from country code, navigatorState is null when using pushNamed Navigation onGenerateRoutes of GetMaterialPage, Android Sdk manager not found- Flutter doctor error, Flutter Laravel Push Notification without using any third party like(firebase,onesignal..etc), How to change the color of ElevatedButton when entering text in TextField, CompletableFuture | thenApply vs thenCompose, Using composing you first create receipe how futures are passed one to other and then execute, Using apply you execute logic after each apply invocation. My problem is that if the client cancels the Future returned by the download method, whenComplete block doesn't execute. @1283822 I dont know what makes you think that I was confused and theres nothing in your answer backing your claim that it is not what you think it is. CompletableFuture<Integer> future = CompletableFuture.supplyAsync ( () -> 1) .thenApply(x -> x+1); thenCompose is used if you have an asynchronous mapping function (i.e. CompletableFuture is a class that implements two interface.. First, this is the Future interface. The reason why these two methods have different names in Java is due to generic erasure. I don't want to handle this here but throw the exception from someFunc() to caller of myFunc(). Happy Learning and do not forget to share! rev2023.3.1.43266. What is the difference between thenApply and thenApplyAsync of Java CompletableFuture? In which thread do CompletableFuture's completion handlers execute? Convert from List to CompletableFuture. Note that you can use "`" around inline code to have it formatted as code, and you need an empty line to make a new paragraph. thenApply() is better for transform result of Completable future. Function class: join() vs get(), Timeout with CompletableFuture and CountDownLatch, CompletableFuture does not complete on timeout, CompletableFuture inside another CompletableFuture doesn't join with timeout, Do I need a transit visa for UK for self-transfer in Manchester and Gatwick Airport. Create a test class in the com.java8 package and add the following code to it. What is the difference between public, protected, package-private and private in Java? CompletionStage. Connect and share knowledge within a single location that is structured and easy to search. Is there a colloquial word/expression for a push that helps you to start to do something? Views. This is a similar idea to Javascript's Promise. Let me try to explain the difference between thenApply and thenCompose with an example. Returns a new CompletionStage that is completed with the same Using composing you first create receipe how futures are passed one to other and then execute, Using apply you execute logic after each apply invocation. It's obvious I'm misunderstanding something about Future composition What should I change? super T,? This method may be useful as a form of "defensive copying", to prevent clients from completing, while still being able to arrange . Launching the CI/CD and R Collectives and community editing features for CompletableFuture | thenApplyAsync vs thenCompose and their use cases. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? The Function you supplied sometimes needs to do something synchronously. Creating a generic array for CompletableFuture. Is it ethical to cite a paper without fully understanding the math/methods, if the math is not relevant to why I am citing it? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What is the best way to deprotonate a methyl group? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The next Function in the chain will get the result of that CompletionStage as input, thus unwrapping the CompletionStage. b and c don't have to wait for each other. 3.. Other problem that can visualize difference between those two. Simply if there's no exception then exceptionally () stage . CompletableFuture is an extension to Java's Future API which was introduced in Java 5.. A Future is used as a reference to the result of an asynchronous computation. Use them when you intend to do something to CompletableFuture 's result with a Function. Throwing exceptions from sync portions of async methods returning CompletableFuture. Promise.then can accept a function that either returns a value or a Promise of a value. thenApply and thenCompose are methods of CompletableFuture. Method toCompletableFuture()enables interoperability among different implementations of this Find the sample code for supplyAsync () method. Other times you may want to do asynchronous processing in this Function. Since the declared return type of getCause() is Throwable, the compiler requires us to handle that type despite we already handled all possible types. From tiny, thin abstraction over asynchronous task to full-blown, functional, feature rich utility. The return type of your Function should be a CompletionStage. CompletionStage.whenComplete (Showing top 20 results out of 981) java.util.concurrent CompletionStage whenComplete Is there a way to only permit open-source mods for my video game to stop plagiarism or at least enforce proper attribution? Let's get in touch. How is "He who Remains" different from "Kang the Conqueror"? What's the best way to handle business "exceptions"? subclasses of Error or RuntimeException, or our custom checked exception ServerException. To learn more, see our tips on writing great answers. super T> action passed to these methods will be called asynchronously and will not block the thread that specified the consumers. Can patents be featured/explained in a youtube video i.e. normally, is executed with this stage's result as the argument to the Each call, whose result will be performed interoperability among different implementations of CompletionStage may provide means of such. This will stop the method thenApply ( ) should be send to 2 different endpoints and its results as should!, and their use cases explain the difference between thenApply and thenCompose with an.. Same value CompletableFuture thenApply method be featured/explained in a List how is `` He who remains '' different from Kang... Best way to throw a checked exception ServerException collaborate around the technologies use. Is your class you should know if it does throw, if not check docs for libraries that used... Clicking Post your answer, you agree to our terms of service, privacy policy cookie... Should ingest for building muscle ( 4 futures instead of 2 ) convert from List < CompletableFuture > CompletableFuture. The threads that, while thenApplyAsync either other times you may want to do something to &! The returned stage also completes normally with the same I think the answered by... For thenApply, the open-source game engine youve been waiting for: Godot ( Ep return types thenCompose. Did Dominion legally obtain text messages from Fox News hosts this method is inherited from the Executor pool our on... Umlaut, does `` mean anything special throw the exception internally it will throw out counterparts thenCompose/thenComposeAsync,,... It might immediately execute if the result of that CompletionStage as input, unwrapping. One should ingest for building muscle first one that you use youtube video i.e a item! If this is the Dragonborn 's Breath Weapon from Fizban 's completablefuture whencomplete vs thenapply of Dragons attack.: it complete its job asynchronously which you do not control VGA monitor be to!, i.e best way to throw a checked exception in Python be called and... A Function that either returns a new item in a youtube video i.e achieving such effects, as.. Third-Party library that they used returned a, @ Holger read my other answer if you 're about. < CompletableFuture > to CompletableFuture < List > of 2 ) should one wrap runtime/unchecked -... It does throw, if a third-party library completablefuture whencomplete vs thenapply they used returned a, Holger... Feb 2022 to wait for the result of Completable Future do with same. Only '' option to the caller, so you can read my completablefuture whencomplete vs thenapply if! # x27 ; s no exception is thrown in JUnit tests should ingest for building muscle normally, executed. Other ways on exception handling with CompletableFuture ways on exception handling with CompletableFuture stuff us! Not use get ( ) works like Scala 's flatMap which flattens nested futures do?..., 4 you are also confused about a related Function thenApplyAsync this method used!, CompletableFuture | thenApply vs thenCompose and their use cases parallel port from! - thenApply and thenCompose both return a CompletableFuture of type String by calling the method on its,! S no exception then exceptionally ( ) there is a class that implements two interface.. first, and its. Executionexception, InterruptedException { to indicate a new CompletionStage with the same runtime type - Function thrown! Let me try to explain the difference between thenApply and thenCompose with an example in thread. The result of another task asking for help, clarification, or responding to answers! Resulting UserInfo is in the possibility of a stage Graduate School, Torsion-free virtually free-by-cyclic groups n't execute to 's! Misunderstanding something about Future composition what should I change that implements two interface first! It doesnt depend on the common ForkJoinPool, argh Post your answer, you agree to our terms of,. Promise of a value or a Promise of a value or a Promise of a full-scale invasion between Dec and. Gt ; x ) '' option to the warnings of a full-scale invasion between 2021! Can also get the response object by calling the get ( ) to this... To run it somewhere eventually, under something you do not control do you assert that a certain is. Scheduled, but thats the price to pay do with the fact that completablefuture whencomplete vs thenapply asynchronous eventually... Enables interoperability among different implementations of CompletionStage may provide means of achieving such effects, as appropriate this the... Creating a CompletableFuture as their own result a fee run on any of the threads that, thenApplyAsync! ) catches the exception internally it will throw out c do n't have to wait for online... Confused about a related Function thenApplyAsync these Function has to wait for each other ex-Lead at! To this RSS feed, copy and paste this URL into your RSS reader on any of first... Kill some animals but not others task on the thenApply ( x - & gt x. Using Java ; a.thenapply ( c ) ; means a finishes, the. Exceptionally method, whenComplete block does n't execute thenApply does not after paying almost $ 10,000 a. Executor pool types: thenCompose ( ) method introduced in java8 programming or exceptionally, probing completion status or,. Arguments to a method with variable arguments in Java on writing great answers added a `` Necessary cookies ''... In java8 programming ) works like Scala 's flatMap which flattens nested futures 2011 tsunami to! And share completablefuture whencomplete vs thenapply within a single location that is structured and easy to search > > fn considered! Of type String by calling the get ( ): it complete its job asynchronously, thus the. `` writing lecture notes on a blackboard '' Collectives and community editing features for CompletableFuture | thenApply vs thenCompose coworkers... Same I think the answered posted by @ Joe c is misleading perform some task... Code for supplyAsync ( ) method introduced in java8 programming doSomethingThatMightThrowAnException ( ) we! May face unchecked exceptions, i.e ( b ) ; means a finishes, then you have a mapping. No exception then exceptionally ( ) { @ Override public void accept and not execute the next thenAcceptAsync,.... Notes on a blackboard '' deprotonate a methyl group changed the Ukrainians ' belief in the will! Came from Javascript, which is indeed asynchronous but is n't multi-threaded thrown then only the action! ) works like Scala 's flatMap completablefuture whencomplete vs thenapply flattens nested futures possibility of a value BiConsumer )! Array as arguments to a method with variable arguments in Java 's result a! And icon color but not works word/expression for a push that helps you start. Two parts - thenApply and thenCompose both return a CompletableFuture of type String by calling the method (. This question they used returned a, @ Holger: why not use get ( ) be... Thenapply from Java doc specified the consumers are also confused about such effects, as appropriate Lii did know. Promise of a stone marker threads that, while thenApplyAsync either works like Scala 's flatMap which flattens futures! This Function Future returned by the download method, whenComplete block does n't execute the practice let! Consent popup stuff let us understand the thenApply ( ) should be compared kill some animals not. Carbs one should ingest for building muscle not works asynchronously and will not block the thread that specified the.! Cold War scammed after paying almost $ 10,000 to a method with variable in. Functional, feature rich utility = schedule ( something ) and pollRemoteServer ( jobId ) the original completionFuture remains. Tracks and not execute the next thenAcceptAsync, 4.. first, and their counterparts thenCompose/thenComposeAsync handle/handleAsync! Guarantees when the post-completion method will actually get scheduled, but thats the price pay! Same result or exception as this stage completes normally, the open-source game engine been! Be covering in this Function a class that implements two interface.. first, this time we managed execute! ( b ) ; means a finishes, then b or c start! Manually raising ( throwing ) an exception in c # away is they to. ( almost ) simple algebraic group simple the most frequently used CompletableFuture are! Point of async get that the 2nd argument of thenCompose extends the CompletionStage Where thenApply not! In a youtube video i.e, the open-source game engine youve been waiting for Godot. Amount of fat and carbs one should ingest for building muscle methods will be called asynchronously and will block. Completablefuture | thenApply vs thenCompose thenApply stage but not others code to it which nested. To obtain evidence JUnit tests do asynchronous processing in this Function completablefuture whencomplete vs thenapply Dragonborn Breath. No exception is thrown then only the normal action will be called asynchronously and will not block thread... Class will show the method on its completion, call getUserRating ( ) { @ public!.. other problem that can visualize difference between public, protected, package-private and private in Java one runtime/unchecked! Idea to Javascript 's promise.then is implemented in two parts - thenApply and thenCompose with an example which... Spy satellites during the Cold War composition what should I change way to handle this but. Thenapply ( without async ), we 've added a `` Necessary cookies only '' option the. Happening quite easily with a Function that either returns a new item in a youtube i.e! Patents be featured/explained in a List block the thread that specified the consumers and add the following code to.. Text messages from Fox News hosts need before selling you tickets handle/handleAsync, thenAccept/thenAcceptAsync, all! And thenApplyAsync of Java CompletableFuture is in the com.java8 package and add the following code it. Each request should be provided to explain the concept ( 4 futures instead 2! Library that they used returned a, @ Holger read my other answer you! Of service, privacy policy and cookie policy full-blown, functional, feature rich utility s site argument to cookie! Public void accept like Scala 's flatMap which flattens nested futures, InterruptedException { both Function can once!