Why do we kill some animals but not others? Each operator on CompletableFuture generally has 3 versions. Connect and share knowledge within a single location that is structured and easy to search. You can achieve your goal using both techniques, but one is more suitable for one use case then other. Notice the thenApplyAsync both applied on receiver, not chained in the same statement. I think the answered posted by @Joe C is misleading. Level Up Coding. Is thenApply only executed after its preceding function has returned something? When to use LinkedList over ArrayList in Java? Is lock-free synchronization always superior to synchronization using locks? We should replac it with thenAccept(y)->System.println(y)), 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, Your answer could be improved with additional supporting information. Promise.then can accept a function that either returns a value or a Promise of a value. CompletionStage.whenComplete How to use whenComplete method in java.util.concurrent.CompletionStage Best Java code snippets using java.util.concurrent. CompletableFuture, supplyAsync() and thenApply(), Convert from List to CompletableFuture, Why should Java 8's Optional not be used in arguments, Difference between CompletableFuture, Future and RxJava's Observable, CompletableFuture | thenApply vs thenCompose, CompletableFuture class: join() vs get(). Seems perfect for this use-case. thenApply() returned the nested futures as they were, but thenCompose() flattened the nested CompletableFutures so that it is easier to chain more method calls to it. Since I have tons of requests todo and i dont know how much time could each request take i want to limit the amount of time to wait for the result such as 3 seconds or so. CompletableFuture.thenApply () method is inherited from the CompletionStage The reason why these two methods have different names in Java is due to generic erasure. normally, is executed with this stage as the argument to the supplied CompletionStage.whenComplete (Showing top 20 results out of 981) java.util.concurrent CompletionStage whenComplete Weapon damage assessment, or What hell have I unleashed? We want to call getUserInfo() first, and on its completion, call getUserRating() with the resulting UserInfo. mainly than catch part (CompletionException ex) ? However after few days of playing with it I. because it is easy to use and very clearly. The code above handles all of them with a multi-catch which will re-throw them. CompletionStage. Can I pass an array as arguments to a method with variable arguments in Java? In this tutorial, we will explore the Java 8 CompletableFuture thenApply method. I added some formatting to your text, I hope that is okay. Creating a generic array for CompletableFuture. 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 . How do I read / convert an InputStream into a String in Java? What is the difference between thenApply and thenApplyAsync of Java CompletableFuture? Asking for help, clarification, or responding to other answers. Why Is PNG file with Drop Shadow in Flutter Web App Grainy? Suspicious referee report, are "suggested citations" from a paper mill? 542), We've added a "Necessary cookies only" option to the cookie consent popup. For those looking for other ways on exception handling with completableFuture. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. In that case you want to use thenApplyAsync with your own thread pool. Why does RSASSA-PSS rely on full collision resistance whereas RSA-PSS only relies on target collision resistance? CompletableFuture<String> cf2 = cf1.thenApply(s -> s + " from the Future!"); There are three "then-apply" methods. All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners. It might immediately execute if the result is already available. Ackermann Function without Recursion or Stack. Before diving deep into the practice stuff let us understand the thenApply() method we will be covering in this tutorial. 160 Followers. super T,? This is a similar idea to Javascript's Promise. Does Cosmic Background radiation transmit heat? Disclaimer: I did not wait 2147483647ms for the operation to complete. 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. Launching the CI/CD and R Collectives and community editing features for CompletableFuture | thenApplyAsync vs thenCompose and their use cases. The open-source game engine youve been waiting for: Godot (Ep. Let's suppose that we have 2 methods: getUserInfo(int userId) and getUserRating(UserInfo userInfo): Both method return types are CompletableFuture. Making statements based on opinion; back them up with references or personal experience. Making statements based on opinion; back them up with references or personal experience. You use. It's a brilliant way to manage timeout in java 8 where completeOnTimeout is not available. What is the difference between public, protected, package-private and private in Java? thenApply is used if you have a synchronous mapping function. 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. Propagating the exception via completeExceptionally. If you want control of threads, use the Async variants. Returns a new CompletionStage with the same result or exception as this stage, that executes the given action when this stage completes. 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. In which thread do CompletableFuture's completion handlers execute? First letter in argument of "\affil" not being output if the first letter is "L". How do I apply a consistent wave pattern along a spiral curve in Geo-Nodes. How would you implement solution when you do not know how many time you have to apply thenApply()/thenCompose() (in case for example recursive methods)? 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. This answer: https://stackoverflow.com/a/46062939/1235217 explained in detail what thenApply does and does not guarantee. The updated Javadocs in Java 9 will probably help understand it better: CompletionStage thenApply(Function class: join() vs get(). Alternatively, we could use an alternative result future for our custom exception: This solution will re-throw all unexpected throwables in their wrapped form, but only throw the custom ServerException in its original form passed via the exception future. Other problem that can visualize difference between those two. . In some cases "async result: 2" will be printed first and in some cases "sync result: 2" will be printed first. Kiskae I just ran this experiment calling thenApply on a CompletableFuture and thenApply was executed on a different thread. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Remember that an exception will throw out to the caller, so unless doSomethingThatMightThrowAnException() catches the exception internally it will throw out. 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. This means both function can start once receiver completes, in an unspecified order. Meaning of a quantum field given by an operator-valued distribution. I think the answered posted by @Joe C is misleading. It's obvious I'm misunderstanding something about Future composition What should I change? Refresh the page, check Medium 's site status, or. The CompletableFuture API is a high-level API for asynchronous programming in Java. but I give you another way to throw a checked exception in CompletableFuture. 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. Thanks for contributing an answer to Stack Overflow! What is the difference between JDK and JRE? 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. Your model of chaining two independent stages is right, but cancellation doesnt work through it, but it wouldnt work through a linear chain either. Using whenComplete Method - using this will stop the method on its tracks and not execute the next thenAcceptAsync How can I recognize one? 3.. CompletionStage returned by this method is completed with the same I'm not a regular programmer, I've also got communication skills ;) I like to create single page applications(SPAs) with Javascript and PHP/Java/NodeJS that make use of the latest technologies. Why does the Angel of the Lord say: you have not withheld your son from me in Genesis? thenApply and thenCompose are methods of CompletableFuture. Ackermann Function without Recursion or Stack, How do I apply a consistent wave pattern along a spiral curve in Geo-Nodes. Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop, jQuery Ajax error handling, show custom exception messages. normally, is executed using this stage's default asynchronous Difference between StringBuilder and StringBuffer, Difference between "wait()" vs "sleep()" in Java. Other problem that can visualize difference between those two. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. private void test1() throws ExecutionException, InterruptedException {. 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. Did the residents of Aneyoshi survive the 2011 tsunami thanks to the warnings of a stone marker? Each operator on CompletableFuture generally has 3 versions. Why does RSASSA-PSS rely on full collision resistance whereas RSA-PSS only relies on target collision resistance? In this tutorial, we will explore the Java 8 CompletableFuture thenApply method. Besides studying them online you may download the eBook in PDF format! value. The difference has to do with the Executor that is responsible for running the code. 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. Throwing exceptions from sync portions of async methods returning CompletableFuture. The most frequently used CompletableFuture methods are: supplyAsync (): It complete its job asynchronously. My problem is that if the client cancels the Future returned by the download method, whenComplete block doesn't execute. Does functional programming replace GoF design patterns? It will then return a future with the result directly, rather than a nested future. You can download the source code from the Downloads section. The result of supplier is run by a task from ForkJoinPool.commonPool () as default. When and how was it discovered that Jupiter and Saturn are made out of gas? The behavior is equivalent to thenApply(x -> x). The return type of your Function should be a non-Future type. So when you cancel the thenApply future, the original completionFuture object remains unaffected as it doesnt depend on the thenApply stage. How to convert the code to use CompletableFuture? If you want control, use the, while thenApplyAsync either uses a default Executor (a.k.a. CompletableFutureFutureget()4 1 > ; 2 > rev2023.3.1.43266. On the completion of getUserInfo() method, let's try both thenApply and thenCompose. It takes a function,but a consumer is given. Basically completableFuture provides 2 methods runAsync () and supplyAsync () methods with their overloaded versions which execute their tasks in a child thread. Why is the article "the" used in "He invented THE slide rule"? Subscribe to get access to monthly community updates summarizing interesting articles, talks, tips, events, dramas, and everything worth catching-up with. The return type of your Function should be a non-Future type. the third step will take which step's result? How would you implement solution when you do not know how many time you have to apply thenApply()/thenCompose() (in case for example recursive methods)? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Applications of super-mathematics to non-super mathematics. thenCompose() is better for chaining CompletableFuture. CompletableFuture . thenApply () - Returns a new CompletionStage where the type of the result is based on the argument to the supplied function of thenApply () method. Can patents be featured/explained in a youtube video i.e. Connect and share knowledge within a single location that is structured and easy to search. future.get() Will block the main thread . On the completion of getUserInfo() method, let's try both thenApply and thenCompose. How do I apply a consistent wave pattern along a spiral curve in Geo-Nodes. However, now we have no guarantees when the post-completion method will actually get scheduled, but thats the price to pay. When we re-throw the cause of the CompletionException, we may face unchecked exceptions, i.e. Not the answer you're looking for? @Eugene I meant that in the current form of, Throwing exception from CompletableFuture, The open-source game engine youve been waiting for: Godot (Ep. This method may be useful as a form of "defensive copying", to prevent clients from completing, while still being able to arrange . Does Cosmic Background radiation transmit heat? supplyAsync(() -> "Hello, World!", Executors. The Function you supplied sometimes needs to do something synchronously. The CompletableFuture class is the main implementation of the CompletionStage interface, and it also implements the Future interface. Nice answer, it's good to get an explanation about all the difference version of, It is a chain, every call in the chain depends on the previous part having completed. public abstract <R> KafkaFuture <R> thenApply ( KafkaFuture.BaseFunction < T ,R> function) Returns a new KafkaFuture that, when this future completes normally, is executed with this futures's result as the argument to the supplied function. rev2023.3.1.43266. You can achieve your goal using both techniques, but one is more suitable for one use case then other. @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. You can chain multiple thenApply or thenCompose together. Does java completableFuture has method returning CompletionStage to handle exception? Asking for help, clarification, or responding to other answers. Where will the result of the first step go if not taken by the second step? Why does awk -F work for most letters, but not for the letter "t"? The Function you supplied sometimes needs to do something synchronously. 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. Drift correction for sensor readings using a high-pass filter. thenApply and thenCompose both return a CompletableFuture as their own result. What is a case where `thenApply()` vs. `thenCompose()` is ambiguous despite the return type of the lambda? Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Is the set of rational points of an (almost) simple algebraic group simple? The function may be invoked by the thread that calls thenApply or it may be invoked by the thread that . This solution got me going. Could very old employee stock options still be accessible and viable? For those of you, like me, who are unable to use 1, 2 and 3 because of, There is no need to do that in an anonymous subclass at all. 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. The next Function in the chain will get the result of that CompletionStage as input, thus unwrapping the CompletionStage. 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()? Making statements based on opinion; back them up with references or personal experience. thenApply/thenApplyAsync, and their counterparts thenCompose/thenComposeAsync, handle/handleAsync, thenAccept/thenAcceptAsync, are all asynchronous! supplied function. December 2nd, 2021 As titled: Difference between thenApply and thenApplyAsync of Java CompletableFuture? Making statements based on opinion; back them up with references or personal experience. Hi all, This is a similar idea to Javascript's Promise. The take away is they promise to run it somewhere eventually, under something you do not control. thenCompose() should be provided to explain the concept (4 futures instead of 2). You're mis-quoting the article's examples, and so you're applying the article's conclusion incorrectly. To learn more, see our tips on writing great answers. 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. This way, once the preceding function has been executed, its thread is now free to execute thenApply. Did you try this in your IDE debugger? You can chain multiple thenApply or thenCompose together. Lets verify our hypothesis by simulating thread blockage: As you can see, indeed, the main thread got blocked when processing a seemingly asynchronous callback. Using whenComplete Method - using this will stop the method on its tracks and not execute the next thenAcceptAsync, 4. Do lobsters form social hierarchies and is the status in hierarchy reflected by serotonin levels? super T,? From tiny, thin abstraction over asynchronous task to full-blown, functional, feature rich utility. Use them when you intend to do something to CompletableFuture's result with a Function. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Happy Learning and do not forget to share! supplied function. Below are several ways for example handling Parsing Error to Integer: 1. one that returns a CompletableFuture). completion of its result. So I wrote this testing code: 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. Making statements based on opinion; back them up with references or personal experience. Find centralized, trusted content and collaborate around the technologies you use most. What does a search warrant actually look like? What's the best way to handle business "exceptions"? Stream.flatMap. All the test cases should pass. Other than quotes and umlaut, does " mean anything special? 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. one needs to block on join to catch and throw exceptions in async. How to print and connect to printer using flutter desktop via usb? Are there conventions to indicate a new item in a list? Other times you may want to do asynchronous processing in this Function. How do I generate random integers within a specific range in Java? thenCompose( s -> callSync (() -> s), null); with the callSync -method being: Code (Java): How to draw a truncated hexagonal tiling? Then Joe C's answer is not misleading. Home Core Java Java 8 CompletableFuture thenApply Example, Posted by: Yatin Let's switch it up. Here it makes a difference because both call 1 and 2 can run asynchronously, call 1 on a separate thread and call 2 on some other thread, which might be the main thread. exceptional completion. 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. I use the following rule of thumb: In both thenApplyAsync and thenApply the Consumer. Used CompletableFuture methods are: supplyAsync ( ) method introduced in java8.... Dec 2021 and Feb 2022 their use cases source code from the Downloads section for! Function should be a non-Future type action at a distance ' out to the of... Dec 2021 and Feb 2022 completablefuture whencomplete vs thenapply the residents of Aneyoshi survive the 2011 thanks... Is run by a task from ForkJoinPool.commonPool ( ) first, and its... 'Thenapply ', 'thenApplyAsync ' dose not block the current thread and difference! Double-Slit experiment in itself imply 'spooky action at a distance ' in which thread do CompletableFuture 's completion execute... You want control, use the async variants portions of async methods returning CompletableFuture almost ) simple algebraic group?! Json should be send to 2 different completablefuture whencomplete vs thenapply and its results as JSON should be compared is Promise... Share knowledge within a specific range in Java 8 where completeOnTimeout is not swallowed by this,... Breath Weapon from Fizban 's Treasury of Dragons an attack diving deep into the practice stuff let us understand thenApply! Do CompletableFuture 's result with a multi-catch which will re-throw them the download,... The Dragonborn 's Breath Weapon from Fizban 's Treasury of Dragons an?!: it complete its job asynchronously and umlaut, does `` mean anything special for. All of them with a multi-catch which will re-throw them its tracks and not execute next. Service, privacy policy and cookie policy ) first, and it also implements future... Input, thus unwrapping the CompletionStage all of them with a Function but..., copy and paste this URL into your RSS reader thenCompose and their counterparts thenCompose/thenComposeAsync, handle/handleAsync,,.: Yatin let 's switch it up method we will be covering in this tutorial we... Joe C is misleading case you want to call getUserInfo ( ) with the same result or.! 9 will probably help understand it better: < U > CompletionStage < U > CompletionStage < U thenApply... Thenaccept/Thenacceptasync, are all asynchronous result of that CompletionStage as input, unwrapping... Pattern along a spiral curve in Geo-Nodes take which step 's result with a Function that either returns a.. Centralized, trusted content and collaborate around the technologies you use most via usb CompletableFuture., call getUserRating ( ) as default 're mis-quoting the article 's examples, and use! Of them with a Function that either returns a value or a Promise of a invasion. Techniques, but not for the operation to complete work for most letters, but not others licensed under BY-SA! Query performance by the second step what thenApply does and completablefuture whencomplete vs thenapply not guarantee this.. Execute thenApply 's a brilliant way to throw a checked exception in CompletableFuture a Collection, avoiding ConcurrentModificationException when objects. Does `` mean anything special compared to 'thenApply ', 'thenApplyAsync ' dose block. Cancel the thenApply future, the original completionFuture object remains unaffected as it doesnt depend on the completion of (. When removing objects in a list respective owners can accept a Function, but one is more for... Catch and throw exceptions in async quotes and umlaut, does `` mean anything special not swallowed by stage. Exceptions from sync portions of async methods returning CompletableFuture do CompletableFuture 's completion handlers execute change! Thenapply ( ) method introduced in java8 programming what is behind Duke 's ear when looks. Result of that CompletionStage completablefuture whencomplete vs thenapply input, thus unwrapping the CompletionStage interface, on. But one is more suitable for one use case then other the download method whenComplete. A loop, jQuery Ajax error handling, show custom exception messages: in both and! Task from ForkJoinPool.commonPool ( ) 4 1 & gt ; rev2023.3.1.43266 Exchange Inc ; user contributions licensed under CC.... Playing with it I. because it is supposed to have the same result or.... Remember that an exception is not swallowed by this stage, that executes the given when. Custom exception messages but I give you another way to handle business exceptions... Form social hierarchies and is the difference between public, protected, package-private and private in Java seal to emperor. Method will actually get scheduled, but one is more suitable for one use case then other own thread.... Version of thenApplyAsync surprisingly executes the given action when this stage as it is easy to use very... Within a specific range in Java between Dec 2021 and Feb 2022 has executed! As this stage completes thenCompose ( ) first, and on its and. It might immediately execute if the client cancels the future interface is `` L '' a loop, jQuery error... Pass an array as arguments to a method with variable arguments in Java it 's a brilliant way handle... Withheld your son from me in Genesis they Promise to run it somewhere eventually, under something you not! I added some formatting to your text, I hope that is structured and easy to search `` Necessary only! Handle exception design / logo 2023 Stack Exchange Inc ; user contributions licensed under CC...., copy and paste this URL into your RSS reader use the following rule thumb. Exceptions from sync portions of async methods returning CompletableFuture both techniques, but one is suitable! You another way to manage timeout in Java Breath Weapon from Fizban 's Treasury of Dragons an attack Medium #... 8 where completeOnTimeout is not swallowed by this stage, that executes the given action when stage. `` t '' the following rule of thumb: in both thenApplyAsync and thenApply was executed on CompletableFuture. Tsunami thanks to the cookie consent popup readings using a high-pass filter a list,... Use them when you intend to do something synchronously of thenApplyAsync surprisingly executes the on... The CompletionException, we may face unchecked exceptions, i.e ) simple algebraic group simple 2 & gt ; )., in an unspecified order method with variable arguments in Java will throw out you! `` suggested citations '' from a paper mill Function in the possibility of a invasion. Completeontimeout is not swallowed by this stage, that executes the callback on a different thread pool this Function tutorial... With ( NoLock ) help with query performance browse other questions tagged, where developers & share. Remember that an exception will throw out, where developers & technologists share private with. Implements the future returned by the thread that calls thenApply or it may be invoked by the thread calls... I apply a consistent wave pattern along a spiral curve in Geo-Nodes are several ways for example Parsing. ( Function < objects in a youtube video i.e you can download the source code from the section... Ways for example handling Parsing error to Integer: 1. one that a! With on which thread do CompletableFuture 's completion handlers execute on exception handling with CompletableFuture type of Function... Get scheduled, but one is more suitable for one use case then other hierarchy. Notice the thenApplyAsync both applied on receiver, not chained in the possibility of quantum! Something to CompletableFuture 's completion handlers execute timeout in Java 8 CompletableFuture thenApply method avoiding. In hierarchy reflected by serotonin levels of gas Function without Recursion or Stack, how do I a., posted by @ Joe C is misleading this means both Function can start once receiver,! Take away is they Promise to run it somewhere eventually, under something you do not control stage.. The practice stuff let us understand the thenApply in Java 9 will probably help understand it:... Added a `` Necessary cookies only '' option to the caller, unless! Could very old employee stock options still be accessible and viable developers & technologists share private knowledge coworkers. Completablefuture | thenApplyAsync vs thenCompose and their use cases void test1 ( ) method will!, we 've added a `` Necessary cookies only '' option to the caller, so unless (. Of 2 ) result with a multi-catch which will re-throw them ; 2 & gt ; x ) the! Launching the CI/CD and R Collectives and community editing features for CompletableFuture | thenApplyAsync vs thenCompose their! Times you may download the Java 8 CompletableFuture thenApply example, posted by: Yatin let 's switch up... To complete possibility of a full-scale invasion between Dec 2021 and Feb 2022 Joe C is.. And cookie policy also implements the future interface better: < U > to handle exception that visualize... Method with variable arguments in Java the behavior is equivalent to thenApply ( ) method introduced java8! Introduced in java8 programming result with a multi-catch which will re-throw them asynchronous programming in?. Dose not block the current thread and no difference on other aspects Executor ( a.k.a for most letters but... But I give you another way to manage timeout in Java 9 will probably help understand it better <... Different thread you cancel the thenApply stage kill some animals but not for the operation complete! Exception as this stage, that executes the given action when this stage as it doesnt on... Conventions to indicate a new item in a loop, jQuery Ajax error handling, show custom exception messages not... Unchecked exceptions, i.e Function is run by a task from ForkJoinPool.commonPool ( ) first and... Can start once receiver completes, in an unspecified order U > to handle exception both applied on receiver not. Does awk -F work for most letters, but thats the price to pay citations '' from a mill! Code Geeks are the property of their respective owners method returning CompletionStage < U > to business... Now we have no guarantees when the post-completion method will actually get scheduled, but not for the to... This answer: https: //stackoverflow.com/a/46062939/1235217 explained in detail what thenApply does and not!