Java 8 CompletableFuture Tutorial with Examples | runAsync() & supplyAsync() | JavaTechie | Part 1

In this tutorial I’ll give you a detailed explanation of CompletableFuture and all its methods using simple examples
This is part 1 video where we discussed below context
What is completableFuture
Why CompletableFuture where already we have Future in java 5
How to create Completablefuture
How to use runAsync and supply Async method with use case
#javatechie #Java8 #CompletableFuture @Multithreading
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[@indraalapati989]

Thank you Basant for making this. I would like to add one more point as completable future by default uses forkjoin pool, this pool has core pool size, if the application is IO intensive it is good to use overloaded constructor (thread pool) to achieve max throughput.

[@Javatechie]

Thanks Indra for this info 👍🏻

[@likithr.n9692]

Can there be a better explanation than this, really awesome man!

[@sateesh9525]

very good video for completable future videos

[@shubhampatidar6116]

I like your code proof for everything - Thanks for your continuity

[@rameshchowdarapally]

Great content

[@psudhakarreddy6548]

Thank you bro. I learned many things from your channel.

[@Javatechie]

Keep learning buddy good to hear this 😍

[@chamithfernando2663]

good explanation

[@neha6000]

Great video again thanks

[@venkatah9847]

Thank you for this video and this will be really helpful for one of my tasks that i am working on. Thank you for your efforts.

[@shahrukshaikh185]

Bravo..!!!!

[@seatconnect224]

best tutorials

[@AxeTvCommunity]

💯
Best explanation compared to any other resource out there
Please keep making videos🙏

[@Javatechie]

Thanks buddy

[@sreetmi1918]

This is a wonderful work I say.. great job basant...

[@abhishakchauhan4580]

Suppose in 1 function you have execute three method inside CF and T1, T2, T3 start
Now on T1 thread, in this method i want to split in more sub task because i have some complex logic in first method
T1. 1
T1. 2
T1. 3

[@sureshsadanala4639]

Great content Basant. Thank you :)

[@aasthadubey1891]

Good content. Thank you .

[@pratishrutipanda6461]

Nice content 👍

[@yogeshchaudhary621]

Thanks for explaining in the simplest way possible.

[@adityavyas6603]

Thanks @Basant thank you for this wonderful tutorial...

[@funcoding1797]

Great bro... tnx alot

[@harish-wi3ts]

Awesome...

[@fitcoder2021]

Great job sir 👍

[@ankxy1]

Great 👍

[@pnworks9186]

Thank You Sir.

[@user-ew9dy9rm8b]

Good explanation keep it up. Include where to shutdown executor

[@insane2539]

Hi java techie bro need video tutorials of
1.Aws batch to implement cron jobs in spring boot
2.Implementing swagger into your microservice and using swagger to generate client call stubs
3.Implementing elastic search for search in your spring boot modules
Please make these tutorials also!!!!

[@Javatechie]

1 & 2 both are good content . I will prepare this but 3rd one already there please have a look

[@insane2539]

@@Javatechie Also bro
3. Implementing amazon codebuild, codepipeline in your microservice in spring boot for CI/CD
4. Implementing Liquibase in spring module to manage schema changes across multiple environments like qa,uat,prod,test

[@Javatechie]

@@insane2539 I am not sure whether you gone through my AWS playlist or not .

[@insane2539]

@@Javatechie ok ill check it

[@AHMADRAZAKHANjava]

Much respect for this video.

[@abhishekwasave9010]

Very well explained video with real example ..thanks it helped alot 👍👏

[@harshverm776]

Thanks Buddy !!!

[@ankitbhatia6128]

Good content..

[@MuresanVladMihail]

💯

[@Moulik23]

Thank you for this awesome topic.

[@9703080696]

Very good explanation 👌

[@niteeshchandanshire4381]

Thank you sir for such explanation 🙏🏻

[@bireshsingh6305]

Thank you so much for this another good content.

[@shyamthe1]

Always on point. Videos from this channel are very practical and easy to follow even the complex concepts. Appreciate the time and effort spent in creating it.
Is there a video that explains different threadpool mechanisms in the executor service?

[@Javatechie]

Thanks buddy , I will cover that as well

[@fabricioaraujo7642]

thanks a lot man !!

[@PradeepKumar-db7pe]

Thanks @JavaTechie! One Question - when you write runAsyncFuture.toCompletableFuture(); Do we conditionally complete it using if? or it is completed by auto-detecting the blocking state?

[@user-nv1bp6fk6z]

Please do a video on to clarify callable, completablefuture and executor.

[@vipulnigam5019]

We can use invokeAll() by adding all these futures in list

[@monsterhuntergo]

Awesome video. I would like to ask the difference between Executor and ExecutorService ...
and Future and FutureTask? When and which one to use? thanks

[@oshogarg5215]

yes , please tell @JavaTechie

[@farhaankazi7134]

Hi Java Techie, You gave the example of runAsync(). In that you called get(). My question is that is correct that the main thread calls get() method of completable future instance, because in that case only CompletableFuture will get chance to complete processing. CompletableFuture has Daemon threads if main thread dies then daemon will be automatically died. If we did not use get method rather we use callback then we have to make the main thread sleep for seconds so that CompletableFuture and its callback will get chance to complete process otherwise daemon threads of CompletableFuture, will die along with main thread of JVM.

[@Mahesh-ry9oe]

Nice tutorial
But we can achieve also using lisnable future it's having addcallback method which is non blocking . We can execute rest of code.

[@kelvintsangxxx7581]

thx

[@vsprasadavantsa7203]

Thanks

[@Javatechie]

Thank you buddy 🤗

[@MuraliM.A.]

Thanks for the video, what is the advantage using own executors over the global poo thread?

[@nikhileshyoutube4924]

Bro make a video on java developer learning path for junior developer's & upcoming fresher's

[@noumaanmohammad1274]

Awesome video. get method wont be blocking main thread until supply async completes its task? If yes can we have whencomplete method?

[@anjalikotha595]

Hi sir can you pls upload junit groovy test classes for unasync methods

[@biswajitmaity1128]

Couple of example showing here , using get() method which are blocking threads , why ? Why are you not using complete() method ?

[@Javatechie]

It's just a demo video to demonstrate all methods buddy

[@preetird8385]

Hi sir could you please make a video on how to mock "supplyAsync" method of completablefuture in Junit class. I'm stuck there and tried everything possible on GitHub and stack overflow. It's failing or going into infinite loop.
The scenario is that supplyAsync method is overridden in the class.

[@Javatechie]

Okay let me try

[@dineshreddyambu]

Spring webflux will also do the same . How it is different from mono and flux?

[@Javatechie]

Dinesh both are non comparable buddy

[@rishikeshkmr]

Can't we use try catch block to handle the exception in case of Future

[@Mike-ci5io]

You can pass a CountDownLatch to the futures to join them

[@shubhamsingla4289]

any one suggest, I don't want to hold my main tread to complete the executions of child treads, so that i can return the response as soon as i started by async method.

[@monsterhuntergo]

Pls help share the link of the next video? thanks so much

[@ainigma100]

Thank you for the video! Is it possible to use this approach assuming the following scenario? We have a method in the service layer that is calling inside 6 external services using feign client. We would like to call them in parallel to reduce the execution time. Keep in mind that each of these API calls is also validation the data they receive. If all the checks of every external API call is ok, then we are fine. In case at least one of the API results does not satisfy our conditions, we have to throw an exception. Can we use this approach or there is another way to do it? Thank you in advance for your time!

[@Javatechie]

Yes absolutely possible if the rest call itself throws an error then it will automatically terminate

[@oshogarg5215]

do you also have a video on Executor Service?

[@Javatechie]

No buddy

[@srikarthikeyakante3152]

Sir, I was trying to implement a scheduler cron job which will take cron expression from database when ever the application starts.but challenge here is how to get cron expression from table with out restart of application.can you make a video on this??

[@mayurkadam1926]

Use quartz scheduler with jdbc implementation

[@Javatechie]

Use @PostConstruct

[@srikarthikeyakante3152]

@@Javatechie
Sry sir I have edited my question..I need to get cron expression from table with out restarting the application.scenariio is I have inserted cron expression for 5 mins and after that I changed to 10 mins.i need to get expression from table with out restarting the spring application.
Thanks

[@tejay1551]

Thanks for this tutorial, I have few queries :
why only one thread used when we pass executor service with thread pool of size 5? is there any way to spin up multiple threads if the file is large?

[@Javatechie]

Since I am playing here with less data . which can be handled by single thread but even I tried to spin up with multiple thread with 1k records but not getting different behaviour.

[@tejay1551]

@@Javatechie may be the behaviour AS IS to Read one file --> one thread.

[@Javatechie]

I will dig this and let you know

[@tejay1551]

@@Javatechie Thank you.

[@smithaitufe6984]

​@@Javatechie thanks for the video. Any feedback from your digging?

[@signorealex]

Thanks for the content 🙂
I think the correct method is complete() and not toCompletableFuture () - mintutes 28:50 ruclips.net/video/GJ5Tx43q6KM/видео.html

[@valkyriegaming478]

How to mock completablefuture in mockito

[@rohitsutar2752]

Still we are blocking main thread

[@arunmenon1025]

where is the 3rd part?

[@ayushjain7555]

the video is not making any sense

[@agarwalr5205]

You need to understand multi-threading concepts first, then this video will make sense and you will be able to co-relate the traditional multithreading and the advantages of using CompletableFuture. I hope this helps.

[@wazeeharaa8100]

Future.cancel ?