Java Strings are Immutable - Here's What That Actually Means

[@etainad0085]

Hey John! I do not leave comments often, so this is a special event. I am currently learning Java at university and at home, and I wanted to tell you how much your videos are helping me. Your simple way of teaching is amazing for new learners, and I find your channel criminally underrated. Keep on uploading, Im sure youll get big on KZbin, a 100%!

[@CodingWithJohn]

Thanks a ton! I'll keep working on it, glad it's helping you!

[@cagan8]

Was going to say the same, usually programming videos are either boring or not engaging and taught well. This is completely opposite, very clear and understandable. Thank you

[@alexwatts1375]

The best creators bubble to the top!

[@snowwhite2146]

@@CodingWithJohn Same here. I have a Java exam in June and your videos are a good revision for me. Many thanks.

[@csgrinds]

Recommend if you're serious about mastering Java that you read e.g. Joshua Bloch rather than watching needlessly long youtube presentations. No criticism of this video intended.

[@MrYourSalvation]

Plus one interesting thing - due to String's immutability and presense of a string pool - the hashCode() method is calculated only the first time and saved as a value inside String object. Therefore when you call hashCode() method second time (e.g. on another variable with the same literal value) - it will just return stored value, no need to calculate hash code again.

[@finmonster5827]

ґалічєнин

[@annaburdanova8307]

Yura, thank you for sharing this interesting fact, the video itself and the comments are a real treasure for a Java learner!

[@fabio.1]

👍

[@CodingWithJohn]

Really cool!

[@mohitsanghai5455]

Thanks a lot for the crisp and clear video, John. Just to summarize String Immutability Benefits - 1) Usage of String pool, saving tons of memory and hashCode calculation 2) safe for multithreading 3) Removes any security threat by not allowing hackers to change referenced string values to cause security issues in the application

[@bobfarker4001]

You basically summarized the summary.

[@Atarian6502]

Thanks for summary. Question regarding #1: Do I understand this correctly: the String pool saves the memory ONLY if you have two or more identical string variables (they point to the same piece of memory), but it wastes memory EVERY time you are changing the strings (it uses new piece of memory for the whole new string even if you change only one letter)?

[@alexz4006]

I always had a question about this topic. I read in a book about java, that strings were immutable, but it never went so much into detail. This is a very good video. Thanks for sharing.

[@NuanDaa]

Dude I’m in bootcamp now for 6 months and no coding background. I just watched your video and I can say you have a best teaching technique that super understandable. You just got a subscriber. Thanks.

[@AdrianWP_T]

I watched your videos countless times while doing my online courses. (I got my degree in 2005 in mechanical engineering but made a serious career change this year) Now, years down the line I'm sitting as an intern as a junior software developer (at age 42), and just watched yet another video. Your explanations are crystal clear. Thanks for the effort in creating them - much appreciated.

[@jiro.nemo.1]

Ive been using Java as a student for nearly 5 years now, and your content has been completely mind-blowing to me. Made me adopt the "I know nothing" attitude and relearn everything.

[@prajwalapattanshetti1743]

I really really don't comment on any KZbin videos as such. But man!!!! The way you explain, your examples, everything is just top notch! I love your videos and have learnt so much from you. Thank you so much!

[@matthewharrison3921]

You have a talent for explaining things in a concise and easy to process manner. Thank you, sir!

[@edwardthng2502]

Im literally studying for AP CS and i couldnt understand why a new string would give a false output, until I came across your video. Your a lifesaver.

[@Hufsa]

first time in this channel and it's absolutely great to dedicate a specific video to talk only about immutable objects in less than 10 minutes, perfectly clear!

[@anluong8103]

Thanks so much. I've just come up with an interview question about this subject this morning. Luckily I watched your video the night before :)

[@LeninMcDonalds]

John you have a gift for teaching. Only a Java master can explain the basics with such clarity to newbies.

[@zishanamin3607]

Protect this man at all costs. Best explanations on Java concepts on the internet

[@rahulshetty9335]

Never even used Java a lot but I have been asked this question in interview. But this is the first time I understood what I was telling the interviewer.

[@swapode]

I think you're kinda missing the main reason why Strings are immutable: You can't really have sensible mutable Strings since you can't change their length without moving everything to newly allocated memory on the heap which is incredibly expensive. I absolutely see your points as benefits, in fact I think Rust has proven that the whole mutable by default approach is a mistake, but it might have been a good idea to go into the actual reason a bit.

[@XD-nj7bc]

I can think of multiple ways that you can change your String length during runtime without coping (at least most of the time). Lists, Allocating more than cou need and and only get new memory when you run out.

[@watertrainer3992]

@@XD-nj7bc allocating more than you need doesn't really solve the problem though, as you'd then just use more than you need, making it more expensive than immutable Strings

[@XD-nj7bc]

@@watertrainer3992 of course it is not cheaper than not mutable strings but you can then change the size without the copying he mentionend.

[@swapode]

@@XD-nj7bc I put the word "sensible" in there for a reason 🙂

[@garybuttherissilent5896]

@@XD-nj7bc yeah he put the word "sensible" in there for a reason bruh

[@misspotato813]

I'm self teaching Java currently, I have a lot of questions about the "whys" and "hows" but currently the JavaDocs are a bit too advanced for me. This really helped!

[@Rational_Human1]

@@jake9854 which dark age r u living in ?

[@CodingWithGhostInCode]

I thought I had a firm grasp of what it means when they say Strings are immutable. After watching this video, Everything i thought i knew went straight outta the window. Thanks John. Way to make things understandable.

[@Fadhelalmalki]

I can swear this man is really a man and know how I think giving the needed answer

[@Veganzza]

Man, you are so amazing. I've read many guides about immutable string but none of them is as clear as your explanation

[@perox1982]

Now Everything has sence. I know many teachers that needs THIS VIDEOS. You Rocks John.

[@praveen123ist]

I think I'll never look back again at why string is immutable, you made it super clear 👌🙏 awesome!!!!

[@rhitamdutta1996]

Holy shit the way you explain things is so simple and lucid, subbed!!!

[@jayskieeee]

i wasn't aware of the benefits of immutability, even though i knew exactly what immutability means. thanks for the tid bits!

[@emekaukwuoma3359]

Learnt a whole lot about string immutability in 7minutes than I have in a year. Lol. Nice one

[@ragore7947]

John, you are [ immutably ] awesome!

[@hanikhellafi4872]

Man I just discovered your channel and I find your content amazing. This is the kind of depth I was looking for regarding string immutability.

[@simonjunior184]

Very helpful demonstration of the concept. I hardly found other videos confusing to understand. Keep up the great job bro!

[@herrbonk3635]

But you find this one confusing to understand??

[@simonjunior184]

@@herrbonk3635 I found this one very clear and straight forward to understand. I went through the video along coding on my IDE.

[@herrbonk3635]

@@simonjunior184 Like most other videos then? (You said you hardly found them confusing, which means that you don't find them confusing.)

[@idkidkidk3333]

Thank you! I will for sure be checking out more of your videos. You explained everything very clearly!

[@wedifilipoprogrammers1073]

I always procrastinated to search about strings being immutable and here its recommended by KZbin

[@drewbruggman]

There was an error i was dealing with ages ago that i couldn't figure out and this video made that error make perfect sense, thank you!

[@JessePoage]

Again, thank you for explaining concepts better than most professors

[@matthewmoore1307]

I love how you’re drawing out with examples as you explain

[@hagnap]

Such a simple topic explained so well, wish they explained it like this in my early CS courses

[@codingweb3904]

Knew all this but still his way of explaining held me till the end.... His way of teaching is just amazing

[@abolfazlsaravani2214]

God I love Java, after 5 years of Java programming, I still love how it works.

[@swastikmohapatra4665]

i have to say i learn something new every day via this channel .

[@drewbhardwaj]

probably the best teacher for coding.🙏🙏

[@billwu7367]

you are the best programmer combining teacher as i ever met!support!

[@SuprousOxide]

Strings are also very commonly used as keys in Map collections. If you insert a value in a map with a key, and then change the key object , you will no longer be able to look up that value with the original key. And with some map types,may have trouble looking up other keys because you have a key stored in the wrong place.

[@wamikgildiev6632]

When you add a value to a map you specify a key (a String in our case). A key is not an object, it's just a pointer to String object in memory. That String object is used to compute a hash code, and to find a bucket index later. So the question is Does Hashmap store a pointer to that String object and why if it already has computed the hash code? I could use Integer or any other class as HashMap key, but they are final.

[@SuprousOxide]

@@wamikgildiev6632 It needs to keep a the actual key around, not just the hash code, because of hash collisions. If two keys have the same hash-code, you need to compare the actual key values to tell which (if either) is pointing at the value you want. If you actually make a copy of the key when you insert it, that would probably work, but I think most implementations assume your key is immutable.

[@THE16THPHANTOM]

the coolest thing about the immutable part(to me) is the multiple thread point. i have come to appreciate that after so many times i have replicated that fact for my objects while trying to avoid the synchronized keyword.

[@dmitriirodionov]

Outstanding and easy to understand explanation! Thank you for this video!

[@mohitjaiswal3526]

Now , I really understand . Why Java Strings are Immutable? Thank you John Sir

[@ronniesuvillian4893]

WOWW!! I am a C++ Developer and i dont even know java, but this discussion was really interesting. Thanks for the information John!!

[@nothappyz]

Worked with java for years, and never knew the pool thing. Amazing

[@learnjavaprogramming7132]

I don't have a words John sir, you are a real teacher I've ever seen , iam very lucky becouse of i found your vedio ☺️☺️

[@haoshecn]

Hi, John. Love your tutorials, but I think there is a little thing you didn’t explain in details here. When you new a string “John”, the object is indeed created in the heap, but “John” is still crated inside string pool. There is a reference inside the object pointing towards “John”. So, you actually created two objects when you use ‘new’ keyword to create a string.

[@arshandubey]

To the point , Every bit of information provided in just 7 minutes. SUBSCRIBED !!!

[@pgm2004]

this man really out here saving my grades. god BLESS

[@BlackHazama]

Never fully understood why strings were immutable or the reason behind them. Thank you!

[@sourav5449]

This is the best explanation of Immutability on youtube You are a gem 💎

[@rajivseeparsad6005]

The best video to understand why String literals are immutable

[@ChaseDetrick]

This was fantastic, thank you so much! I've been struggling a lot in my comp sci classes because the professor refuses to go over theory, so this is wonderful :) You've won a very very faithful subscriber haha.

[@rajeshchattopadhyaya2805]

I am currently learning Java your videos give deeper understanding of Java thank you very much!

[@h-girlradio4699]

Thank you so much for explaining this!! I never truly got a grasp on what was meant by Strings being immutable but you explained it perfectly!!

[@TG-ri3mu]

Wow, wow, wow, FINALLY the explanation of immutable strings that l was looking for sooo long time! THANK YOU!

[@sb-zn4um]

finally an understanding of why .equals was always preferential over ==

[@pkmishra2359]

Thanks john , finally I understand why Strings are immutable .

[@thunderstruck2727]

Love your concise, clear, and informative videos! I normally try to read Oracle Tutorial Trails, but these videos are faster on certain topics. Plus you include great examples. Thank you!

[@CodingWithJohn]

Those are good too (as they should be, coming directly from Oracle) and I've used them to do some research on various topics I've done videos for. But yeah, often it's easier to watch a video on it. Thanks!

[@thunderstruck2727]

@@CodingWithJohn thanks for the reply! I’m a Comp Sci graduate who just finished my first year working a software job.

[@maresolaris]

Finally! I finally understand what immutable actually means. Thank you for this clear explanation.

[@fantasy9960]

Wow, this is the best explanation I can find on youtube! thank you john

[@huseyinkadioglu]

Simple and clear explanation John. I appreciate your work and effort. Amazing stuff!

[@Bersling]

just completing the trifecta: yay, somebody does cool java videos about interesting topics in 2021 - subscribed!

[@marciomartins4111]

I am a brazilian developer. I see your videos to strudy English. Thank you.

[@CuriousCyclist]

Thank you for taking the time to make this video. I have liked, subscribed and am commenting. Cheers!

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you are the best java teacher that i saw on the youtube because you are cleary explain what is the behind theory thank you very much 🤩💖

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Man! This is a mind blowing info for me. Never thought about this before! Thanks.

[@odravison]

Hey John, just to tell you that your video saved my carrer! Thanks a lot! Keep going.

[@CodingWithJohn]

Wow, I'd love to hear how!

[@odravison]

@@CodingWithJohn hahah! OK. I shouldn't be that extremy in my words haha! I just watched this video just before I taken an interview within an interviwer who asked for me this concept in Java xD

[@odravison]

@@CodingWithJohn haha, ok, I could be extreme when I said that haha. But this video helped me to answer my interview question correctly thhhxxx

[@StobbeTime]

Your an awesome teacher! I remember studying this topic in my book and could not understand it till now. Thanks.

[@alexandrprodan8794]

Wow, it's great video! Informative, comprehensive and not boring. Thank you very much!

[@prajwaltirpude8582]

Great video. It is so clear now and books never explain it such great way

[@mirzaaqeel]

Crystal clear with examples. Hats off to you.

[@hannahdlh1]

The best explanation for this topic that I've seen so far. Thank you!!

[@MIchaelArlowe]

One of the saner innovations given to us by Java.

[@DragonKlavier]

Omg. I just discovered this magnifique Chanel to really learn Java.... thanks!!!!

[@1dagmawi]

You are easy to understand and always to the point. Glad I found you. Keep up the good work. Cheers.

[@Jakypbekovich]

Trifecta is done! Very well explained, thank you!

[@CodingWithJohn]

Thanks much!

[@ЛёхаБодунов-б7ж]

Yesterday I had this question in my mind and today I saw this video. Thanks!

[@vasundharachintha5037]

Your videos are amazing!!You really do make the concepts clear!!Thanks for such an amazing content.

[@tiagosilva9795]

What a great explanation! Thanks John!

[@Gabriel-bu1qq]

Hey John, just amazing channel, i subscribed already. I finally could understand this. just a tip in my humble opinion, if you could speak not so fast i had to slowdown the video a little bit to follow your thoughts, but its just a tip the rest its perfect. Congratulations!!!!!

[@bonnydavis6730]

Beautifully explained. Very informative . Thank you !!

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Love how the KZbin recommendations algo work.glad i came across this video.. so well explained.. thank you

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Amazing content. I dont usually comment but your way of teaching is extraordinary! Keep them good contents coming.

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Hello John, your videos are incredibly helpful. I have learnt a lot from your videos. Do keep up the good work, you will go big on KZbin one day.

[@JustinBieberFanSA]

John, I love your videos. Thank you. Studying for the OCA at the moment and you explain these concepts so well that I do not need to study them after watching the video. I understand it, which means I remember it forever because I understand how it works. I really appreciate your help!

[@codyprevatt]

You explain things extremely well.

[@Coccoutube]

Excellent lesson John! I'm learning a lot with you :)

[@jayeshgautam7101]

Well, finally my confusion is gone. Thank you sir.

[@arturillosmeriglia8029]

Great explanation! Easy to follow, clear and concise. You earned a new subscriber!

[@codewithfelix3940]

mn tnx fo the vid , am also a java programmer , i could hav noticed tht u r a software engineer even if u didnt say coz bro u r good .

[@Wolf-u5o]

Thank you John.. That was the best explanation for understanding what immutable means

[@SSHHoneypot]

I knew that this exists, but I never understood why. Now I do. Thanks :)))

[@amaanmohammad1190]

Simple Concise and to the point.

[@hackmasters617]

Loved the explanation John!

[@manojbhat1440]

I was getting recommendation for one week but i didn't watch .Today i got the same question in the exam😭😭

[@abhiniveshl676]

Crisp and clear

[@dylangovender]

This was awesome. Thanks, John!

[@vm1662]

Okay. You are awesome and so is this channel. Thanks a lot!!!!

[@PradumTiwari28]

Really your teaching of every concept is legendary keep Doing good work