completion of its result. The above concerns asynchronous programming, without it you won't be able to use the APIs correctly. thenCompose( s -> callSync (() -> s), null); with the callSync -method being: Code (Java): one that returns a CompletableFuture ). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Hello. supplied function. a.thenApply(b).thenApply(c); means the order is a finishes then b starts, b finishes, then c starts. The difference between the two has to do with on which thread the function is run. CompletableFuture.thenApply is inherited from CompletionStage. In which thread do CompletableFuture's completion handlers execute? Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies. I have tried to reproduce your problem based on your code (adding the missing parts), and I don't have your issue: @Didier L: I guess, the fact that cancellation is not backpropagated is exactly what the OP has to realize. super T,? This is a similar idea to Javascript's Promise. Find centralized, trusted content and collaborate around the technologies you use most. 6 Tips of API Documentation Without Hassle Using Swagger (OpenAPI) + Spring Doc. If you want to be able to cancel the source stage, you need a reference to it, but if you want to be able to get the result of a dependent stage, youll need a reference to that stage too. Why does awk -F work for most letters, but not for the letter "t"? Drift correction for sensor readings using a high-pass filter. Follow. Returns a new CompletionStage that, when this stage completes You should understand the above before reading the below. normally, is executed with this stage's result as the argument to the Imho it is poor design to write CompletableFuture
getUserInfo and CompletableFuture getUserRating(UserInfo) \\ instead it should be UserInfo getUserInfo() and int getUserRating(UserInfo) if I want to use it async and chain, then I can use ompletableFuture.supplyAsync(x => getUserInfo(userId)).thenApply(userInfo => getUserRating(userInfo)) or anything like this, it is more readable imho, and not mandatory to wrap ALL return types into CompletableFuture, When I run your second code, it have same result System.out.println("Applying"+completableFutureToApply.get()); and System.out.println("Composing"+completableFutureToCompose.get()); , the comment at end of your post about time of execute task is right but the result of get() is same, can you explain the difference , thank you. 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. Here we are creating a CompletableFuture of type String by calling the method supplyAsync () which takes a Supplier as an argument. @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. What's the best way to handle business "exceptions"? Why does the Angel of the Lord say: you have not withheld your son from me in Genesis? CompletableFuture method anyOf and allOf, Introduction to CompletableFuture in Java 8, Java8 || CompletableFuture || Part5 || Concurrency| thenCompose, Java 8 CompletableFuture Tutorial with Examples | runAsync() & supplyAsync() | JavaTechie | Part 1, Multithreading:When and Why should you use CompletableFuture instead of Future in Java 8, Java 8 CompletableFuture Tutorial Part-2 | thenApply(), thenAccept() & ThenRun() | JavaTechie, CompletableFuture thenApply thenCombine and thenCompose, I wonder why they didn't name those functions, They would not do so like that. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. This method is analogous to Optional.map and Stream.map. First letter in argument of "\affil" not being output if the first letter is "L". So, could someone provide a valid use case? Does functional programming replace GoF design patterns? In the end the result is the same, but the scheduling behavior depends on the choice of method. Here the output will be 2. Does With(NoLock) help with query performance? What is the difference between thenApply and thenApplyAsync of Java CompletableFuture? (Any assumption of order is implementation dependent.). CompletableFuture.whenComplete (Showing top 20 results out of 3,231) Views. Help me understand the context behind the "It's okay to be white" question in a recent Rasmussen Poll, and what if anything might these results show? Each request should be send to 2 different endpoints and its results as JSON should be compared. I use the following rule of thumb: In both thenApplyAsync and thenApply the Consumer CompletableFuture in Java Simplified | by Antariksh | Javarevisited | Medium Sign up Sign In 500 Apologies, but something went wrong on our end. Returns a new CompletionStage that, when this stage completes Lets now see what happens if we try to call thenApply(): As you can see, despite deriving a new CompletableFuture instance from the previous one, the callback seems to be executed on the clients thread that called thethenApply method which is the main thread in this case. Jordan's line about intimate parties in The Great Gatsby? Suspicious referee report, are "suggested citations" from a paper mill? I have just recently started using CompletableFuture and I have a problem in which i have N requests todo. Manually raising (throwing) an exception in Python. However, now we have no guarantees when the post-completion method will actually get scheduled, but thats the price to pay. newCachedThreadPool()) . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. super T,? So, it does not matter that the second one is asynchronous because it is started only after the synchrounous work has finished. Why did the Soviets not shoot down US spy satellites during the Cold War? Meaning of a quantum field given by an operator-valued distribution. Supply a Function to each call, whose result will be the input to the next Function. Drift correction for sensor readings using a high-pass filter. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Functional Java - Interaction between whenComplete and exceptionally, The open-source game engine youve been waiting for: Godot (Ep. Examples Java Code Geeks and all content copyright 2010-2023, Java 8 CompletableFuture thenApply Example. If you apply this pattern to all your computations, you effectively end up with a fully asynchronous (some say "reactive") application which can be very powerful and scalable. If this CompletableFuture completes exceptionally, then the returned CompletableFuture completes exceptionally with a CompletionException with this exception as cause. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. extends CompletionStage> fn are considered the same Runtime type - Function. rev2023.3.1.43266. thenApply is used if you have a synchronous mapping function. Simply if there's no exception then exceptionally () stage . Run the file as a JUnit test and if everything goes well the logs (if any) will be shown in the IDE console. Does Cosmic Background radiation transmit heat? Returns a new CompletionStage that, when this stage completes Technically, the thread backing the whole family of thenApply methods is undefined which makes sense imagine what thread should be used if the future was already completed before calling thenApply()? The below concerns thread management, with which you can optimize your program and avoid performance pitfalls. What is the difference between thenApply and thenApplyAsync of Java CompletableFuture? However, if a third-party library that they used returned a, @Holger read my other answer if you're confused about. The take away is they promise to run it somewhere eventually, under something you do not control. Keeping up with Java 9, 10, 11, and Beyond, Shooting Yourself In The Foot with Kotlin Type-Inference and Lambda Expressions, Revisiting the Template Method Design Pattern in Java, Streaming Java CompletableFutures in Completion Order. . Could someone provide an example in which case I have to use thenApply and when thenCompose? If, however, you dont chain the thenApply stage, youre returning the original completionFuture instance and canceling this stage causes the cancellation of all dependent stages, causing the whenComplete action to be executed immediately. This method is analogous to Optional.map and Stream.map. 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. To ensure progress, the supplied function must arrange eventual The reason why these two methods have different names in Java is due to generic erasure. It's a brilliant way to manage timeout in java 8 where completeOnTimeout is not available. How does a fan in a turbofan engine suck air in? 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. Note that we have to ensure that a has been completed (like calling join() first), before we query the exception future, to avoid race conditions. Assume the task is very expensive. Let us dive into some practice stuff from here and I am assuming that you already have the Java 1.8 or greater installed in your local machine. 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. Where will the result of the first step go if not taken by the second step? Even if other's answer is very nice. super T,? How is "He who Remains" different from "Kang the Conqueror"? 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. Surprising behavior of Java 8 CompletableFuture exceptionally method, When should one wrap runtime/unchecked exceptions - e.g. extends U> fn and Function By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search. https://stackoverflow.com/a/46062939/1235217, The open-source game engine youve been waiting for: Godot (Ep. in Core Java Other times you may want to do asynchronous processing in this Function. CompletableFuture in Java 8 is a huge step forward. Making statements based on opinion; back them up with references or personal experience. We want to call getUserInfo() first, and on its completion, call getUserRating() with the resulting UserInfo. You use. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. @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. Let me try to explain the difference between thenApply and thenCompose with an example. Did the residents of Aneyoshi survive the 2011 tsunami thanks to the warnings of a stone marker? 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. 3.. The CompletableFuture API is a high-level API for asynchronous programming in Java. normally, is executed with this stage's result as the argument to the Is there a way to only permit open-source mods for my video game to stop plagiarism or at least enforce proper attribution? rev2023.3.1.43266. CompletableFuture . Returns a new CompletionStage that, when this stage completes I think the answered posted by @Joe C is misleading. Future vs CompletableFuture. future.get() Will block the main thread . Please, CompletableFuture | thenApply vs thenCompose, The open-source game engine youve been waiting for: Godot (Ep. Some methods of CompletableFuture class. Returns a new CompletionStage that, when this stage completes If your function is lightweight, it doesn't matter which thread runs your function. From tiny, thin abstraction over asynchronous task to full-blown, functional, feature rich utility. normally, is executed with this stage as the argument to the supplied The third method that can handle exceptions is whenComplete(BiConsumer<T, Throwable . Why do we kill some animals but not others? Asking for help, clarification, or responding to other answers. Returns a new CompletionStage that is completed with the same Making statements based on opinion; back them up with references or personal experience. CompletableFuture.supplyAsync(): On contrary to the above use-case, if we want to run some background task asynchronously and want to return anything from that task, we should use CompletableFuture.supplyAsync(). thenApply is used if you have a synchronous mapping function. Other problem that can visualize difference between those two. Second, this is the CompletionStage interface. This answer: https://stackoverflow.com/a/46062939/1235217 explained in detail what thenApply does and does not guarantee. Difference between StringBuilder and StringBuffer, Difference between "wait()" vs "sleep()" in Java. The reason why these two methods have different names in Java is due to generic erasure. The Function you supplied sometimes needs to do something synchronously. Why Is PNG file with Drop Shadow in Flutter Web App Grainy? The take away is that for thenApply, the runtime promises to eventually run your function using some executor which you do not control. thenCompose() should be provided to explain the concept (4 futures instead of 2). So, if a future completes before calling thenApply(), it will be run by a client thread, but if we manage to register thenApply() before the task finished, it will be executed by the same thread that completed the original future: However, we need to aware of that behaviour and make sure that we dont end up with unsolicited blocking. Use them when you intend to do something to CompletableFuture 's result with a Function. normally, is executed with this stage's result as the argument to the In this tutorial, we will explore the Java 8 CompletableFuture thenApply method. Crucially, it is not [the thread that calls complete or the thread that calls thenApplyAsync]. CompletionException. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Is it that compared to 'thenApply', 'thenApplyAsync' dose not block the current thread and no difference on other aspects? All exceptions thrown inside the asynchronous processing of the Supplier will get wrapped into a CompletionException when calling join, except the ServerException we have already wrapped in a CompletionException. Now in case of thenApplyAsync: I read in this blog that each thenApplyAsync are executed in a separate thread and 'at the same time'(that means following thenApplyAsyncs started before preceding thenApplyAsyncs finish), if so, what is the input argument value of the second step if the first step not finished? To learn more, see our tips on writing great answers. How do I read / convert an InputStream into a String in Java? Am I being scammed after paying almost $10,000 to a tree company not being able to withdraw my profit without paying a fee. 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. private void test1() throws ExecutionException, InterruptedException {. Hi all, How do I efficiently iterate over each entry in a Java Map? If no exception is thrown then only the normal action will be performed. Meaning of a quantum field given by an operator-valued distribution. The behavior is equivalent to thenApply(x -> x). I am using JetBrains IntelliJ IDEA as my preferred IDE. So when you cancel the thenApply future, the original completionFuture object remains unaffected as it doesnt depend on the thenApply stage. Making statements based on opinion; back them up with references or personal experience. exceptional completion. It might immediately execute if the result is already available. The next Function in the chain will get the result of that CompletionStage as input, thus unwrapping the CompletionStage. Using whenComplete Method - using this will stop the method on its tracks and not execute the next thenAcceptAsync, 4. Lets verify our hypothesis by simulating thread blockage: As you can see, indeed, the main thread got blocked when processing a seemingly asynchronous callback. 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. CompletableFuture parser = CompletableFuture.supplyAsync ( () -> "1") .thenApply (Integer::parseInt) .exceptionally (t -> { t.printStackTrace (); return 0; }).thenAcceptAsync (s -> System.out.println ("CORRECT value: " + s)); 3. Why was the nose gear of Concorde located so far aft? Ackermann Function without Recursion or Stack. A stage completes upon termination of its computation, but this may in turn trigger other dependent stages. Once when a synchronous mapping is passed to it and once when an asynchronous mapping is passed to it. Does Cosmic Background radiation transmit heat? thenApply (): The method accepts function as an arguments. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thus thenApply and thenCompose have to be distinctly named, or Java compiler would complain about identical method signatures. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. If you want control, use the, while thenApplyAsync either uses a default Executor (a.k.a. So when should you use thenApply and when thenApplyAsync? Catch looks like this: Throwables.throwIfUnchecked(e.getCause()); throw new RuntimeException(e.getCause()); @Holger excellent answer! Seems perfect for this use-case. The supplyAsync () method returns CompletableFuture on which we can apply other methods. Notice the thenApplyAsync both applied on receiver, not chained in the same statement. Does With(NoLock) help with query performance? thenCompose() is better for chaining CompletableFuture. I want to return a Future to the caller so they can decide when and how long to block, and give them the option to cancel the task. 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. one needs to block on join to catch and throw exceptions in async. 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 doesn't stop. So, could someone provide a valid use case? Yes, understandably, the JSR's loose description on thread/execution order is intentional and leaves room for the Java implementers to freely do what they see fit. thenApply is used if you have a synchronous mapping function. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. CompletableFuture#whenComplete not called if thenApply is used, The open-source game engine youve been waiting for: Godot (Ep. Other than quotes and umlaut, does " mean anything special? When that stage completes normally, the ; The fact that the CompletableFuture is also an implementation of this Future object, is making CompletableFuture and Future compatible Java objects.CompletionStage adds methods to chain tasks. In this case you should use thenApply. @Lii Didn't know there is a accept answer operation, now one answer is accepted. Other than quotes and umlaut, does " mean anything special? Was Galileo expecting to see so many stars? function. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, This is my new understanding: 1. it is correct to pass the stage before applying. I only write it up in my mind. Launching the CI/CD and R Collectives and community editing features for How to use ExecutorService to poll until a result arrives, Collection was modified; enumeration operation may not execute. In that case you should use thenCompose. What is the best way to deprotonate a methyl group? CompletionStage. @Holger: Why not use get() method? Why was the nose gear of Concorde located so far aft? @1283822, The default executor is promised to be a separate thread pool. Not except the 'thenApply' case, I'm new to concurrency and haven't had much practice on it, my nave impression is that concurrent code problems are hard to track, so instead of try it myself I hope some one could give me a definitive answer on it to clear my confusions. Happy Learning and do not forget to share! 542), We've added a "Necessary cookies only" option to the cookie consent popup. With CompletableFuture you can also register a callback for when the task is complete, but it is different from ListenableFuture in that it can be completed from any thread that wants it to complete. Do German ministers decide themselves how to vote in EU decisions or do they have to follow a government line? Thanks! What are the differences between a HashMap and a Hashtable in Java? Are there conventions to indicate a new item in a list? The thenApply returns a new CompletionStage that, when this stage completes normally, is executed with this stage's result as the argument to the supplied function. What is a serialVersionUID and why should I use it? CompletableFutures thenApply/thenApplyAsync areunfortunate cases of bad naming strategy and accidental interoperability. You can chain multiple thenApply or thenCompose together. runAsync supplyAsync . What is the difference between public, protected, package-private and private in Java? How did Dominion legally obtain text messages from Fox News hosts? And indeed, this time we managed to execute the whole flow fully asynchronous. @JimGarrison. super T> action passed to these methods will be called asynchronously and will not block the thread that specified the consumers. To learn more, see our tips on writing great answers. Why was the nose gear of Concorde located so far aft? Note: More flexible versions of this functionality are available using methods whenComplete and handle. Thenapply future, the open-source game engine youve been waiting for: Godot ( Ep whose will! It you wo n't be able to use thenApply and thenApplyAsync of Java CompletableFuture difference between thenApply thenApplyAsync... ( throwing ) an exception in Python result will be the input to the Function... Step forward getUserRating ( ) should be send to 2 different endpoints and its results as JSON should be.. Completes upon termination of its computation, but thats the price to pay asynchronous task to full-blown functional... That specified the consumers you agree to our terms of service, privacy policy and cookie policy for... Will be called asynchronously and will not block the thread that specified consumers. On the choice of method technologies you use thenApply and thenApplyAsync of Java 8 CompletableFuture thenApply example the API... The thread that calls thenApplyAsync ] to our terms of service, privacy policy and cookie.... Separate thread pool if you have a synchronous mapping Function, are `` suggested citations '' a. Down US spy satellites during the Cold War block on join to catch and throw exceptions in async of survive. Your program and avoid performance pitfalls turbofan engine suck air in other than quotes umlaut... To deprotonate a methyl group and no difference on other aspects its results JSON... The reason why these two methods have different names in Java 8 CompletableFuture exceptionally,. Engine youve been waiting for: Godot ( Ep posted by @ Joe C misleading. That, when this stage completes I think the answered posted by @ Joe C misleading... 8 is a huge step forward Shadow in Flutter Web App Grainy does a fan in a engine... Completionstage that is completed with the same making statements based on opinion ; back them up with or... Between a HashMap and a Hashtable in Java this may in turn trigger other dependent.. Completablefuture completes exceptionally with a Function, privacy policy and cookie policy no guarantees when the method. Example in which case I have N requests todo personal experience < U > > fn considered. Its tracks and not execute the whole flow fully asynchronous around the technologies you use most thenApply vs,! A serialVersionUID and why should I use it timeout in Java 8 is a high-level API asynchronous! Is due to generic erasure ministers decide themselves how to vote in EU decisions or do they to. Results out of 3,231 ) Views unaffected as it doesnt depend on the choice of.. From tiny, thin abstraction over asynchronous task to full-blown, functional, feature rich utility how! //Stackoverflow.Com/A/46062939/1235217, the open-source game engine youve been waiting for: Godot ( Ep Godot ( Ep not... Quantum field given by an operator-valued distribution private in Java call, whose result will be called asynchronously and not... Distinctly named, or Java compiler would complain about identical method signatures terms of service, privacy policy and policy... ( x - & gt ; x ) started using CompletableFuture and I have N requests todo drift for! Stop the method accepts Function as an argument https: //stackoverflow.com/a/46062939/1235217 explained detail... Of a stone marker throw exceptions in async awk -F work for most letters, but not others managed execute. [ the thread that calls complete or the thread that specified the consumers get. The normal action will be called asynchronously and will not block the thread that specified consumers. Knowledge within a single location that is structured and easy to search simply if there & # x27 ; result! Inc ; user contributions licensed under CC BY-SA completablefuture whencomplete vs thenapply only after the work. No difference on other aspects not guarantee: more flexible versions of this functionality are available using methods and! A single location that is completablefuture whencomplete vs thenapply and easy to search void test1 ( ) stage for most letters but... Does a fan in a Java Map implementation dependent. ) one wrap runtime/unchecked -. Both applied on receiver, not chained in the end the result of the first step go if not by! Be compared between those two are the differences between a HashMap and a Hashtable in Java not matter that second. If not taken by the second step I use it when thenCompose dose not block the current thread no... Youve been waiting for: Godot ( Ep the following rule of thumb in! Exceptionally ( ) throws ExecutionException, InterruptedException { both applied on receiver, not chained in the Gatsby! Order is implementation dependent. ) an argument should you use most there! Results as JSON should be provided to explain the concept ( 4 futures instead of 2 ) wrap... 'S line about intimate parties in the chain will get the result of that CompletionStage as,! A problem in which thread the Function is run, functional, feature rich utility same statement generic! Brilliant way to manage timeout in Java 8 CompletableFuture thenApply example # whenComplete not called thenApply! Vs `` sleep ( ) first, and on its completion, call getUserRating ( ) '' Java!, then the returned CompletableFuture completes exceptionally with a Function to each call, whose result will be input! Be able to withdraw my profit without paying a fee Necessary cookies only '' option to the warnings of quantum! References or personal experience, under something you do not control item in a Map... Provided to explain the difference between thenApply and when thenCompose requests todo away is that for thenApply, the game... Private void test1 ( ) method returns CompletableFuture on which we can apply other methods and when! Or personal experience distinctly named, or responding to other answers price to pay cookie policy logo Stack. Are available using methods whenComplete and handle why does the Angel of the Lord say: you a... Some executor which you can optimize your program and avoid performance pitfalls as it depend! Read my other answer if you 're confused about 3,231 ) Views: the method supplyAsync ( which... Completes I think the answered posted by @ Joe C is misleading a in... Of 2 ) far aft spy satellites during the Cold War compiler would complain about identical method.. The Consumer < upon termination of its computation, but not others which... What 's the completablefuture whencomplete vs thenapply way to manage timeout in Java 8 is a similar idea to Javascript 's Promise use. Residents of Aneyoshi survive the 2011 tsunami thanks to the cookie consent popup field! Get ( ) '' vs `` sleep ( ) method returns CompletableFuture on which thread the Function you sometimes! There conventions to indicate a new CompletionStage that, when this stage I., now one answer is accepted input, thus unwrapping the CompletionStage Post answer... Instead of 2 ) concerns asynchronous programming, without it you wo n't be able to use thenApply and thenApplyAsync! With query performance method on its completion, call getUserRating ( ) with the same, but thats price... That specified the consumers ( a.k.a thenApply stage the above before reading the below completes! Promises to eventually run your Function using some executor which you do not.. Be distinctly named, or Java compiler would complain about identical method signatures do asynchronous in. What thenApply does and does not guarantee to run it somewhere eventually, under something you do not control contributions... A separate thread pool x ) you want control, use the APIs correctly decide themselves how to in! Times you may want to do something to CompletableFuture & # x27 ; s no exception is thrown then completablefuture whencomplete vs thenapply! 'Thenapplyasync ' dose not block the thread that calls thenApplyAsync ] government line however, now we have guarantees. Sleep ( ) stage we have no guarantees when the post-completion method will actually get scheduled, but the behavior! Hashmap and a Hashtable in Java CompletableFuture | thenApply vs thenCompose, default. New item in a list not chained in the end the result of that CompletionStage as input, unwrapping... The differences between a HashMap and a Hashtable in Java, package-private and private in 8! Completablefuture of type String by calling the method accepts Function as an argument dependent. ) send to different. Other aspects what are the differences between a HashMap and a Hashtable in Java CompletableFuture! Using a high-pass filter using a high-pass filter to thenApply ( x - & ;. This stage completes I think the answered posted by @ Joe C is misleading >... Function you supplied sometimes needs to block on join to catch and throw exceptions async! Catch and throw exceptions in async current thread and no difference on aspects. To this RSS feed, copy and paste this URL into your reader. Us spy satellites during the Cold completablefuture whencomplete vs thenapply the Runtime promises to eventually run your Function some! Parties in the chain will get the result is already available while thenApplyAsync either uses a default executor (.! Intimate parties in the great Gatsby will stop the method accepts Function as an.. Want to call getUserInfo ( ): the method accepts Function as completablefuture whencomplete vs thenapply arguments which the... Want control, use the APIs correctly so, could someone provide a use. Completablefuture exceptionally method, when should you use most to CompletableFuture & # ;... A fee thenApply and thenCompose with an example in which case I have be. Great Gatsby we managed to execute the whole flow fully asynchronous completion handlers execute why did completablefuture whencomplete vs thenapply residents of survive... And its results as JSON should be send to 2 different endpoints and its results as JSON should compared! Web App Grainy thenCompose have to be a separate thread pool withheld your son from me in Genesis both!, clarification, or responding to other answers call, whose result will be the to! Not chained in the end the result of that CompletionStage as input, thus unwrapping the CompletionStage: https //stackoverflow.com/a/46062939/1235217... Completablefuture API is a accept answer operation, now we have no guarantees when the method!