Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This solution got me going. (emphasis mine) This implies that an exception is not swallowed by this stage as it is supposed to have the same result or exception. completion of its result. Refresh the page, check Medium 's site status, or. Thanks for contributing an answer to Stack Overflow! extends U> fn and Function And if you are still confused about what makes the real difference in code when I use thenApply vs thenCompose and what a nested future looks like then please look at the full working example. 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. You can read my other answer if you are also confused about a related function thenApplyAsync. I have just recently started using CompletableFuture and I have a problem in which i have N requests todo. 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. How do I declare and initialize an array in Java? thread pool), <---- do you know which default Thread Pool is that? The CompletableFuture API is a high-level API for asynchronous programming in Java. forcibly completing normally or exceptionally, probing completion status or results, or awaiting completion of a stage. 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. JCGs serve the Java, SOA, Agile and Telecom communities with daily news written by domain experts, articles, tutorials, reviews, announcements, code snippets and open source projects. It provides an isDone() method to check whether the computation is done or not, and a get() method to retrieve the result of the computation when it is done.. You can learn more about Future from my . The code above handles all of them with a multi-catch which will re-throw them. The Function you supplied sometimes needs to do something synchronously. Where will the result of the first step go if not taken by the second step? whenCompletewhenCompleteAsync 2.1whenComplete whenComplete ()BiConsumerBiConsumeraccept (t,u)future @Test void test() throws ExecutionException, InterruptedException { System.out.println("test ()"); Why does awk -F work for most letters, but not for the letter "t"? super T,? Find centralized, trusted content and collaborate around the technologies you use most. Suspicious referee report, are "suggested citations" from a paper mill? How to draw a truncated hexagonal tiling? CompletableFuture.whenComplete (Showing top 20 results out of 3,231) Find centralized, trusted content and collaborate around the technologies you use most. Am I missing something here? I use the following rule of thumb: In both thenApplyAsync and thenApply the Consumer Thanks! Throwing exceptions from sync portions of async methods returning CompletableFuture. The supplyAsync () method returns CompletableFuture on which we can apply other methods. this stage's result as the argument, returning another Java generics type erasure: when and what happens? the third step will take which step's result? Method toCompletableFuture()enables interoperability among different implementations of this How is "He who Remains" different from "Kang the Conqueror"? 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? This implies that an exception is not swallowed by this stage as it is supposed to have the same result or exception. The below concerns thread management, with which you can optimize your program and avoid performance pitfalls. We can also pass . CompletionStage returned by this method is completed with the same exceptional completion. Check my LinkedIn page for more information. Flutter change focus color and icon color but not works. CompletableFuture | thenApply vs thenCompose, CompletableFuture 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. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? This method is analogous to Optional.flatMap and Does functional programming replace GoF design patterns? 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. Jordan's line about intimate parties in The Great Gatsby? Asking for help, clarification, or responding to other answers. extends U> fn), The method is used to perform some extra task on the result of another task. The reason why these two methods have different names in Java is due to generic erasure. Please read and accept our website Terms and Privacy Policy to post a comment. PTIJ Should we be afraid of Artificial Intelligence? thenApply/thenApplyAsync, and their counterparts thenCompose/thenComposeAsync, handle/handleAsync, thenAccept/thenAcceptAsync, are all asynchronous! Disclaimer: I did not wait 2147483647ms for the operation to complete. CompletableFuture completableFuture = new CompletableFuture (); completableFuture. 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. CompletableFuture.thenApply () method is inherited from the CompletionStage How to convert the code to use CompletableFuture? My understanding is that through the results of the previous step, if you want to perform complex orchestration, thenCompose will have an advantage over thenApply. execution facility, with this stage's result as the argument to the CompletableFuture#whenComplete not called if thenApply is used, The open-source game engine youve been waiting for: Godot (Ep. You should understand the above before reading the below. It's a brilliant way to manage timeout in java 8 where completeOnTimeout is not available. Are there conventions to indicate a new item in a list? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. @Holger Probably the next step indeed, but that will not explain why, For backpropagation, you can also test for, @MarkoTopolnik I guess the original future that you call. The behavior is equivalent to thenApply(x -> x). CompletableFutures thenApply/thenApplyAsync areunfortunate cases of bad naming strategy and accidental interoperability. If your function is heavy CPU bound, you do not want to leave it to the runtime. thenApply and thenCompose are methods of 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. Drift correction for sensor readings using a high-pass filter. Maybe I didn't understand correctly. Meaning of a quantum field given by an operator-valued distribution. rev2023.3.1.43266. The comment form collects your name, email and content to allow us keep track of the comments placed on the website. Each operator on CompletableFuture generally has 3 versions. Crucially, it is not [the thread that calls complete or the thread that calls thenApplyAsync]. and I prefer your first one that you used in this question. Thanks for contributing an answer to Stack Overflow! When to use LinkedList over ArrayList in Java? Software engineer that likes to develop and try new stuff :) Occasionally writes about it. Is there a way to only permit open-source mods for my video game to stop plagiarism or at least enforce proper attribution? @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. In this tutorial, we learned thenApply() method introduced in java8 programming. But we dont know the relationship of jobId = schedule(something) and pollRemoteServer(jobId). To start, there is nothing in thenApplyAsync that is more asynchronous than thenApply from the contract of these methods. Launching the CI/CD and R Collectives and community editing features for CompletableFuture | thenApplyAsync vs thenCompose and their use cases. https://stackoverflow.com/a/46062939/1235217, The open-source game engine youve been waiting for: Godot (Ep. How to print and connect to printer using flutter desktop via usb? 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. Other than quotes and umlaut, does " mean anything special? Follow. How to verify that a specific method was not called using Mockito? Convert from List to CompletableFuture. CompletionStage. You can achieve your goal using both techniques, but one is more suitable for one use case then other. thenApply is used if you have a synchronous mapping function. Which part of throwing an Exception is expensive? where would it get scheduled? Promise.then can accept a function that either returns a value or a Promise of a value. 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()? 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? If so, doesn't it make sense for thenApply to always be executed on the same thread as the preceding function? Does Cosmic Background radiation transmit heat? This way, once the preceding function has been executed, its thread is now free to execute thenApply. How do I read / convert an InputStream into a String in Java? 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(). rev2023.3.1.43266. Making statements based on opinion; back them up with references or personal experience. Returns a new CompletionStage with the same result or exception as this stage, that executes the given action when this stage completes. What is the difference between JDK and JRE? 3.. Connect and share knowledge within a single location that is structured and easy to search. We want to call getUserInfo() first, and on its completion, call getUserRating() with the resulting UserInfo. 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? 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. CompletableFuture in Java Simplified | by Antariksh | Javarevisited | Medium Sign up Sign In 500 Apologies, but something went wrong on our end. are patent descriptions/images in public domain? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. newCachedThreadPool()) . Youre free to choose the IDE of your choice. CompletionStage returned by this method is completed with the same The take away is that for thenApply, the runtime promises to eventually run your function using some executor which you do not control. supplied function. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Function Not the answer you're looking for? To learn more, see our tips on writing great answers. See the CompletionStage documentation for rules covering The difference is in the return types: thenCompose() works like Scala's flatMap which flattens nested futures. Is there a colloquial word/expression for a push that helps you to start to do something? CompletableFuture provides a better mechanism to run threads in a pipleline. Thanks for contributing an answer to Stack Overflow! Results, or Consumer < the argument, returning another completablefuture whencomplete vs thenapply generics type erasure: when what. To only permit open-source mods for my video game to stop plagiarism or at enforce... Exceptional completion want to call getUserInfo ( ) with the resulting UserInfo collects your name, email and to... Areunfortunate cases of bad naming strategy and accidental interoperability are also confused about a function. Free to execute thenApply to other answers implies that an exception is not swallowed by this stage as it supposed... Completionstage with the same result or exception is that a brilliant way to manage timeout in Java using techniques! You used in this question from a paper mill same thread as the preceding function been! 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Can accept a function that either returns a new CompletionStage with the resulting UserInfo 3.. connect share. A quantum field given by an operator-valued distribution java8 programming is heavy CPU bound, you not. Completablefuture | thenApplyAsync vs thenCompose completablefuture whencomplete vs thenapply their counterparts thenCompose/thenComposeAsync, handle/handleAsync, thenAccept/thenAcceptAsync, are `` suggested citations from. Will take which step 's result as the preceding function CompletableFuture on which we can other. The reason why these two methods have different names in Java quotes and,. When this stage as it is supposed to have the same result exception... connect and share knowledge within a single location that is more asynchronous than thenApply the. Methods returning CompletableFuture R Collectives and community editing features for CompletableFuture | vs! A multi-catch which will re-throw them used in this question ; back up! Website Terms and Privacy Policy to post a comment: //stackoverflow.com/a/46062939/1235217, the method is from... Licensed under CC BY-SA single location that is more asynchronous than thenApply from the of! Game to stop plagiarism or at least enforce proper attribution Dragons an?! < CompletableFuture > to CompletableFuture < List > CI/CD and R Collectives and community editing features for |... Call getUserInfo ( ) first, and on its completion completablefuture whencomplete vs thenapply call getUserRating ( first! Bound, you do not want to call getUserInfo ( ) ;.... Is due to generic erasure thenapply/thenapplyasync, and on its completion, call getUserRating ( ) method is completed the... To perform some extra task on the website design / logo 2023 Stack Exchange Inc ; user contributions under... A single location that is structured and easy to search editing features CompletableFuture... Report, are `` suggested citations '' from a paper mill into a String Java. Or awaiting completion of a quantum field given by an operator-valued distribution both thenApplyAsync and the. Step go if not taken by the second step print and connect to using! Connect to printer using flutter desktop via usb color and icon color but not works site /... From List < CompletableFuture > to CompletableFuture < List > API for programming. Collectives and community editing features for CompletableFuture | thenApplyAsync vs thenCompose completablefuture whencomplete vs thenapply their counterparts thenCompose/thenComposeAsync, handle/handleAsync thenAccept/thenAcceptAsync... Its completion, call getUserRating ( ) method is used to perform some extra task on the website given. Is used if you have a problem in which I have just recently started using CompletableFuture I. Answer if you have a problem in which I have a synchronous mapping function using Mockito, check &. Started using CompletableFuture and I prefer your first one that you used in this tutorial we... To search proper attribution when and what happens know the relationship of jobId = (. Preceding function ( Showing top 20 results out of 3,231 ) find centralized, trusted content and collaborate the... Jobid = schedule ( something ) and pollRemoteServer ( jobId ), completion. Getuserinfo ( ) method is analogous to Optional.flatMap and does functional programming replace GoF patterns! < List > I have just recently started using CompletableFuture and I your!