Java Custom Exceptions Tutorial - It's Way Easier Than You Think

Full tutorial on creating custom exceptions in Java!
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Custom exceptions can be intimidating if you're relatively new to Java. But creating your own Java exceptions is way easier than you may think.
If you're confused about how to go about creating your own exceptions in Java, or to find out best practices for doing so, you're in the right place!
Learn or improve your Java by watching it being coded live!
Hi, I'm John! I'm a Lead Java Software Engineer and I've been in the programming industry for more than a decade. I love sharing what I've learned over the years in a way that's understandable for all levels of Java learners.
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[@CodingWithJohn]

Thanks to Mailgun for sponsoring this video! Head to mailgun.com/john to try Mailgun free today. If you have any questions, be sure to ask here!

[@DaxterSnickers]

Nice, you actually did a video for what i asked for. Youre the best, thank you!

[@libertymedicalcommunicatio4908]

We’ll done. You’re a natural teacher!

[@turuus5215]

I'm reading "Java All in One for Dummies," and I had trouble wrapping my head around the "throwing exceptions" chapter. Thank you for clearing up my confusion. Your lessons are intuitive and straight to the point. Your delivery is amazing.

[@Adrastus_]

thanks john. I've been watching more and more of your videos as a java beginner, and as I watch them, each one makes me more certain to get your java bootcamp. these videos are truly great and if im going to learn even more, it will be immensely helpful to know the fundamentals are coming from you.

[@mustapharaimilawal8053]

Hello John, thanks a lot for this video. I watched it some months ago and I missed some points you made about passing Throwable into the custom exception constructor but watching it again now made me realized how detailed this video is. Thanks a lot.

[@enfieldli9296]

Wow, cleared some of my confusions, good stuff! Thank you so much John!

[@hummerzone]

i love your simple but clear explanations,,thanks John

[@samreensaleemudeen1220]

love the way you've explained this concept... I didn't learn this properly in C++ so ... I'm really happy that I could understand it so quickly... thank you so for that 😊

[@Abhijeet_Tripathi_]

Struggled with this topic for so long..... You're an amazing teacher 🙌🏻🙌🏻🙇‍♂️.... Thank you so much🙏🏻

[@hunelysium]

Thank you for making all wonderful videos on Java!! All of them very clarifying!

[@jaredschwery167]

Thanks John! Helpful as always :)

[@blubbfisch98]

After going through several videos, this is the first truly informational one. No weird jumps, well-spoken English and not a lot of noise around the main topic. I know this video is old by now - but keep it up! :P

[@sabei221b]

I'm obsessed with your content, amazing job!!

[@ohmohm7884]

Simple, informative, and clear. Brilliant. Thank you!

[@erezswickley2139]

Amazing. You really helped me wrap my head around this concept. Thank you so much, I really appreciate it.

[@fatmamohmed58]

Before this video i was suffering with Exception but now i find it so easy thank you for your effort

[@fcbarcatv-ou4ww]

ive been watching many of your video for the past 3 hours, youre an actual legend

[@user-yr4bu7gm9s]

Brilliant teaching, every word you spoke in this video had intense meaning to it, Thank you

[@AnnaAdamczyk]

Thank you for another easy to understand video!

[@yasminaitmaksene5230]

What a simple way to explain things ! Thank's a lot. 😁😁

[@edgardom.7455]

Hi John, I recently discovered your channel, and I loved the way you expose the content. Learning to program when you are close to 50 years of age, is a much more affordable challenge with the help of channels like yours, thank you very much for your time and dedication. Greetings from Chile.

[@ravireddyism]

I appreciate your courage coz guys in 20's are finding hard to understand Java but you in your 50's have accepted this challenge to learn java at your age. I wish you all the best and I hope with your dedication and interest you will master it.

[@SUMITYADAV-cy9hf]

you made java so easy man ..thanks for your contribution

[@mikelkumar6680]

Thanks for your work

[@aniolmalin]

that runtime stuffe just solved me a task i thought is difficult, thanks

[@nikhilagrawal9217]

Really helpful. Thank you sir.

[@nudaykiran2014]

Simple and clear explanation

[@SaiNadhBolloju]

Thanks for your efforts in here… making complex things simple to understand. A request, please explain time and space complexities in your terms.

[@diegoi1313]

Thank you for this well informed video. I was able to complete my assignment after watching it.

[@pranavkarpe9742]

Can you make a video on collection framework. Loved the way you explain the concept.

[@chetanraj1950]

Thnak You for this lecture.

[@lefruitcake]

if you hadn't explained the extends RuntimeException part, wouldn't have saved me in a pinch! Thank you so much!

[@sudharshan32nft]

Thanks John

[@paranormaledits9526]

Watching this before exam, you're a great teacher.

[@VictorHernandez-qt2xx]

Great content. Please add the benefits of catching it in your catch block. Also point out that extending from IllegalArgumentException changes the custom to a runtime excpetion.

[@fabricio.entringer]

Good video. Direct and amazing!

[@preetamvarun9219]

Thank you!

[@Righteous_Companions]

Thanks sir 😊 That was helpful 🙂 I was having trouble making custom exception, Thanks to this video finally its done

[@CodingWithJohn]

Not so hard once you know!

[@Another0neTime]

Great explanation.

[@SayanRick100]

Thanks man.... I'm watching your video from India... it's really helpful

[@pipocosounds]

Your channel is gold wow!

[@Eva-kt3tu]

thank you so much

[@thelinkguys2925]

Wish you have a full spring boot course!

[@matiasmoresi5040]

Hey John! Loving all your videos! Could you do a tutorial on Streams? 🤩 Thank you so much!

[@boxacuva]

I think Streams are a little bit more complex than exception Handling. At least in Theory. But i would recommend u to write all existing Stream Classes down (Sub/Base Classes, Decorators, Reader/Writers,...) and put them in Relation.

[@LTZMSYAL]

Hi John! Thank's for your great tutos. Could you make a video on the binary search algorithm? Think it would be helpful. Thank's :)

[@abhineveash]

Finally got it🎉

[@mohannadarslan2478]

Thank you

[@ruralthunder8854]

Have you ever considered making videos on data structures in Java? Thanks for the videos!

[@xxxguruji5211]

Thank you .

[@javalady]

Thanks that was really usefull

[@johngeorge9296]

hey john this tutorial was so informative within a short duration you have covered many important topics! do you offer J2EE and spring related course? besides highfive to you that we have same name....

[@berkcanulubas1318]

thank you for th great videos

[@ayushchakraborty1921]

Easy to understand! Will remember the *don'ts* 😂👍🏻

[@developer9049]

Thanks :)

[@DeepakSharma-mi8nz]

Hey John you are awesome

[@blasm1713]

john john john, your videos are inspiring

[@ayushkumar-cl7co]

Watched all videos...ur teaching style is awesome.....plz bring videos on Spring Boot

[@piyushash]

Yes, absolutely i am also waiting for Spring boot playlists

[@MariusSipanu]

Very good video

[@samuelbullon3792]

loved it

[@LeafyConversations]

You are awesome!!!!!

[@s6031417]

YES

[@vicke909]

Hi, can you do a javaFX tutorial or perhaps a short video showing how to begin? Thank you : )

[@prasadgujar2007]

I purchased your course, however, now i realized you have more detail knowledge on youtube

[@ravikumarray338]

We should neither extend Throwable and nor use it in Catch block. Reason why not to use Throwable in catch block is that it will catch Error also which is not desired .

[@familyshare3724]

And thus passing Error to custom exception constructor should fail to compile. In other words: Exception cause, not Throwable cause.

[@boxacuva]

I Agree there is really no need to extend Throwable.

[@blacksheep1337]

nice u a real goood teacher

[@Sudheer_662]

hi john ,can u pls make a video on java Streams api

[@Speiger]

I found that mojang used exceptions very weirdly. If a network packet is in the wrong thread, they append it in a thread and basically throw a exception that does no logging to stop processing of said network packet. (Ignoring the implication on how bad it is to throw hundreds of exception per second, it is still a really interesting concept)

[@KolomiecSergeyK]

Hello, thanks for a nice video. One point that I want to understand, do you think that validation should be handled by exception? As far as I know exception is quite heavy for JVM. Maybe better just return true or false in case something valid or not.

[@JorgetePanete]

exceptions (throwing and not throwing) have gotten lighter at least

[@lakshyasaharan5348]

Looking forward to your hair sponsorship.

[@Learn_IT_with_Azizul]

useful content... but I don't like ads, and thanks for time stamps

[@kezug]

Is there an inherent overhead (performance degradation of the app) when using Exceptions and Custom Exception handling for "business" error handling as opposed to just putting in validations in code without exception handling? (Assume a large application with many business rules and just trying to come to terms with making a decision of when to use custom Exceptions for business validations vs never)

[@ipodtouch470]

Could you show exception handling in possibly a larger code base? I understand the concepts but fail to put them into the big picture. For example why use an exception at all instead of an if statement since the possibility of getting a negative age is common .

[@JorgetePanete]

Take for example a method that returns a number that is either valid or broken, how do you check that assuming you don't know what the method does? The method could have instead a BrokenNumberGeneratorException in the method and you could catch it

[@masudulalam2515]

How do you handle filter level exceptions which are thrown from filter and can't be caught in @RestControllerAdvice/@ControllerAdvice annotated class?

[@luwamabraham4338]

I don't now how to thank you. GBU

[@keydiram]

Hi, Can you add a Maven tutorial? Thanks.

[@rasZam]

why did our custom exception extend Exception? why not RuntimeException?

[@HanWae363]

If you dont extend exception wouldn't a try catch block also not work if it were trying to catch all Exceptions? Since most exceptions inherit from a root parent Exception?

[@familyshare3724]

Constructor takes Throwable or Exception cause?

[@holdendewit7088]

Wouldnt using super in the constructor invoke the constructor of the super class (that is to say effectively you have AgeLessThanZeroException e = new InvalidArgumentException(mes, cause); )? If thats the case is there any real benefit to making local object variables and methods instead?

[@kamal-xd7id]

By creating so many custom exceptions, wouldn't it be so unmanageable? Rather we use or define a little more generic or superclass of specific exceptions and pass in the details as param?

[@ErenYagdran]

I'm so fortunate to see a java developer hailing from the last ice age :)

[@amirulidzham]

Hi John. Thank you for such a great video. Really appreciate it. I just have one question, sorry that it's not related to video, is there any way to have a dynamic set attribute in OOP? I'm kinda interested like what offered in Laravel's Eloquent method (the insert method). All you need to do is create new object, set attribute object from instance, call save method. Not sure if Spring has something to like this to offer.

[@paveljavorek2076]

Hi Not sure if is this the answer you looking for, but spring boot contains Spring Data JPA, when you can save atribute or objects to the database throught repository object

[@amirulidzham]

@@paveljavorek2076 wow. I gotta try it out myself. Thanks for the valuable information.

[@boxacuva]

This Question is a little bit confusing. Do you mean an ORMapper like EF/NHibernate or do you mean aop? Or Simply dynamic Keyword like in c#.

[@amirulidzham]

@@boxacuva I've no idea of what are you talking. It not confusing at all. Maybe you should take a look at Laravel first specifically at eloquent method of saving data

[@boxacuva]

@@amirulidzham wdym its just a normal ORMapper Feature. Maybe it would help to explain what that feature does instead of letting ppl looking it up for you. So they can help. I just gonna assume its a normal CRUD transaction done in a higher level langugage. Edit: Just googled it and found a php ORMapper. Not sure if that is what u asking for. So gl

[@joelpww]

God sent

[@azamvlogs84]

Anyone know which eclipse is he using??

[@slimandahra4294]

I will find out..i have eyes 👀 everywhere That's funny 😂 Well done

[@yasminaitmaksene5230]

Hello John I have a problem trying to use my custom exceptions. In some places of my method , when I try to throw a new custom exception, I'm getting this error : Unhandled exception type myCustomException. Eclipse suggest to add a try catch block to it. Any idea why I'm getting this ? Thank's

[@CodingWithJohn]

Any exception you make (unless it's extending RuntimeException) is what's called a checked exception in Java. That means it either had to be declared in the method signature that it can be thrown, or handled with a try/catch. Check out my video on checked and unchecked exceptions to learn more! kzbin.info/www/bejne/mHSzdJ-vfNiJnsU

[@Pacvalham]

throw new NullPointerException(); //shortcut for throwing a null pointer exception: throw null;

[@adibpeerzade5657]

can you put videos on jdbc?

[@jovictor3007]

Thanks, I thought exceptions were some magic, I didnt realise they were just classes.

[@CodingWithJohn]

Yeah I know what you mean, it feels like such a mystery until you learn that.

[@jagathis2863]

Hii sir please upload the tic tac toe dynamic size java program?

[@alisbai4376]

have anybody noticed the font colors in Intellij mach the Java logo colors?

[@DadaKhan1912]

Sir, How can we print the custom exception in catch block like e.printStackTrace() or sout(e);

[@CodingWithJohn]

Depends on what you would like to print. sout(e) doesn't give you very much (I haven't tried it until just now, but looks like it just prints the class name of the exception). e.printStackTrace is often useful for debugging (although logging tools handle printing the stack trace for an exception their own way in larger applications), so that is more likely what you want. You can also print out the message on your exception if there is one, which you can find at myException.getMessage();

[@DadaKhan1912]

@@CodingWithJohn Thank you sir for replying for my message with a good explanation 😊

[@sidforreal]

Good to see you finally ditched eclipse 😛😛

[@CGDW2]

But at which point is it worth it to actually create your own custom Exception rather than just using (going by this example) IllegalArgumentException with a message that says something like "age must be positive". Would one ever put additional functionality in a custom Exception? Aside from the comedic value of hilariously named exceptions that your co-workers would hopefully run into (itWasYourJobToImplementThisException), why bother?

[@stephenJpollei]

It is probably worth creating your own custom Exception when you can have actual value in using that type in a "catch". Maybe an example of potentially good "additional functionality" could be extra fields that store information that "catch" block could use. Like a MessageNotReceivedException could take a reference to the message so that the catch block can requeue it.

[@CGDW2]

@@stephenJpollei Ah right, I can see how that would be useful.

[@familyshare3724]

In many backend projects (say microservices with many inputs and outputs), I distinguish between client validation exceptions (invalid external input), upstream exceptions (like database failure), retryable exceptions and non-retryable exceptions. I then want every transaction to have exactly one and only one final status: happy (info) or one fatal exception (log error) type. No matter the service type, it's similar to HTTP or FTP response codes: 200 ok, 404 not found, different 4** client errors, and 5** (this service failed) or upstream/gateway temporary or unrecoverable failure.

[@familyshare3724]

Many projects decide whether to handle checked or unchecked exceptions exclusively on day one. Checked Exceptions should be handled immediately by the caller. If a project team (for whatever reason, including lack of discipline) won't consistently handle checked exceptions, then IMO the team should decide to wrap (all) checked exceptions as unchecked (either as a rethrown RuntimeException cause or custom exception extending some runtime exception). I recommend a strict consistent pattern, rather than developer whim ("hey this existing exception sounds kinda like it fits our problem"). If you're not sure, then wrap all exceptions as RuntimeException (or a single common custom exception) until you refactor later when/if you do know what you want.

[@familyshare3724]

Maybe it's worth noting that many, including architects at Sun, considered the combination of checked and unchecked exceptions a compromise and regrettable failed experiment. Checked exceptions help write reliable fail-proof code. But if not properly understood, not properly handled, checked exceptions often lead to terrible programming habits (like catch and ignore at worst to catch and rethrow at uh, typical annoying tedium). The Throwable, Error, Exception, RuntimeException inheritance structure is a (necessary?) bastardization that also encourages (allows for) poor coding practice (exception mis-handling).

[@abdulrashidsinancu1630]

How to know if an exception is checked (Compile Time ) or Unchecked (Run Time) Ans: If a class extends Exception ->It is known as Compile Time or Checked Exception If a class extends RuntimeException ->It is known as RunTime or Unchecked Exception

[@timm1328]

Extending Exception is usually a bad idea. Checked exceptions were a failed experiment and only leads to empty global catch clauses strewn through the code. Instead custom exceptions can extend RuntimeException. Furthermore throws clauses on methods are a pain in the ass when trying to pass method references.

[@Y3llowMustang]

What VS Code theme is he using?

[@CodingWithJohn]

This is IntelliJ, with the standard theme. The only change is I darkened the background a little.

[@belayketema9921]

Wow

[@ivankobyuk8385]

From Ukrainian dev with huge appreciation! / Від українського розробника з вдячністю!

[@larryd9577]

NegativeAgeException.

[@CodingWithJohn]

Even better!

[@socaljusticewarrior558]

I like the part where you point at the camera and go out of focus and then come back. That was very cinematic.

[@CodingWithJohn]

Yep, new camera! Besides that part, it's pretty hard to tell the difference between this and all my other videos which were just recorded with a phone.