#10 - How HashMap works internally || Popular java interview question on collection (HashMap)

In this video, I have explained How HashMap works internally, what is hashing and HashCode, what is indexing and how is it calculated from Hashcode?
This is a very popular java interview question on collection (HashMap).
References taken from:
Java 8 API Doc
Oracle Java 8 Source Code
Geeks of geeks
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[@soumyajit443]

I have read about this from multiple resources.But I had never seen it in real 'how exactly it works'.You have explained so beautifully.Its just amazing. I would say you are "THE DRONACHARYA" (who was was royal preceptor to the Kauravas and Pandavas.)
Thank you so much for making this awesome video.Its so clear and precise.Thanks

[@naveenautomationlabs]

Most welcome:) keep learning 👍😃

[@soumyajit443]

@@naveenautomationlabs I want to get strong in logic building.I appeared for an interview but did not get selected in first round.They asked to write a program which would take input an Integer array having only zeros and ones and output will be sorted Integer like 000011111.I could not answer it.
Actually Naveen,I need a proper plan and guidance to get strong in my programming skills.Please guide me if you provide any personal training I would like to enroll for it as its high time and I want a change in my career.

[@rachakatladheer9059]

@@soumyajit443 use Sort Class
int arr[] = {0,1,0,1,0,1,0,1,1,0,0,1};
Arrays.sort(arr);
System.out.println(Arrays.toString(arr));
o/p - [0,0,0,0,0,0,1,1,1,1,1,1]

[@anushavenkatesan685]

@@soumyajit443 check his website. He s taking live classes

[@rd3316]

🙌take a bow Naveen . I searched this on internet and no one has explained it in such an easy way like you .

[@sureshgarine]

I appreciate your research on Hashmap implementation under the hood, I remembered my college day's Hashing concept implementation, now I see in reality in debug mode. Thanks, Naveen. this is called bridging the gap between institution and industry. :)

[@naveenautomationlabs]

Thanks for your valuable comment. Thanks for your motivation.

[@abhiPn9160]

Thanks sir....i searched many time for working of hashmap. But Didn't satisfied with explanation all they have. But after ur video now I am cleared about hashmap. Your explanation in simple and better 🙏 thnks sir

[@Pratyush.K.R]

the best hashmap internal working video on youtube. OP🙌

[@sharvilpatil8742]

This is the best explanation one can ever get on Hashing and Hashmap. Great explanation Naveen!

[@ambicaponnaluri7743]

All my queries regarding Harshmap were cleared after watching this.Awesome work😊
Keep rocking..
Thankyou much Naveen

[@swapnakadam1822]

The best explanation on How hashmap works internally, I have seen so many videos but I get confused instead of understanding but this is PERFECT....Thank you...

[@rakeshdora6]

Really appreciate your work and awesome explanation i saw several videos for hashmap implementation and work flow. But this is the BEST.

[@viveksinghbais4133]

Thank you, sir, I can't even imagine how much hard work and research are required to create such knowledgeable content. thanks so much

[@gita3354]

Excellent explanation Naveen . I was so scared to learn the collections concept in java. But you have made it like a cupcake . Thanks much for your time and effort. I don't think even the paid courses will give this much explanation for each nuke and corners.

[@muzammilkhan382]

Thankyou Naveen Sir for your explanation! After banging my head for hours, and reading articles, finally found your video and understood how it works.

[@prabhakarreddy9180]

Entire RUclips ur explanation is just awesome

[@ruch3719]

Very well and crisp with what is required and the clarity of topic stays longer in mind ..with so neat and clear explanation.Hope you keep posting more content on data structures and common topic which are required longer

[@sandeshkumar9156]

RUclips really has some great teachers. If I get teachers like Naveen I would love to study all day.

[@shubhambansal6903]

Chal jhoota 😂

[@sandeshkumar9156]

@@shubhambansal6903 😂😂😂Why bro

[@jatinsharma3792]

You always saves me in difficult situation where understanding is not easy. :D Thanks!!

[@shrutijoshi6496]

@naveenautomationlabs loved the explanation . Its actually amazing how you take this valuable time in explaining and putting out the most relevant explanation. Actually a FAN of yours.

[@naveenautomationlabs]

Thanks Shruti. Glad that it was helpful 😀

[@lockdowndiaries4090]

super. simple and clear explanation. i have searched many videos. nothing compared to urs. great and thank you so much for helping us out

[@Ranjan-Singh89]

Thanks, Naveen for creating this whole java collection video series. In this series, you have really explained each and every collection framework topic in an awesome way and In fact, I am following a couple of automation tutors on RUclips but no one has explained these topics in such an easy and understanding way. 😊👍👍

[@farazahmad9009]

Glad I came across this video. What a wonderful explanation. Thanks a lot!!

[@sujith6323]

Explanation followed by the important notes was very helpful. Really appreciate this Quality content.

[@suyogdtalathi924]

Thanks !! After searching more for hashmap internal structure this one is the best explanation

[@utpalkanti]

Excellent explanation. Many many thanks for this kind of video. Recollecting my old college day topics now...

[@Fortheluvoffood]

really good explanation... learning from your channel is very much easier than reading stuff on internet and reading books... precise explanation with good examples clears the concept easily rather than getting confused in it... appreciate your efforts and your easiness towards teaching these concepts... you do it so confidently and so easily... thankyou so much...

[@dhareppasasalatti7102]

The best out of the best Explanation I have even seen on this hashmap.. Thank you sir for the effort.. It's was 💯💯

[@funved3371]

You have explained this complex topic in a way which is very easy to understand.
Thank you very much sir.

[@nithyar767]

You have done a wonderful job Naveen ! Thanks!

[@kumargaurav4362]

In Java 8, HashMap replaces linked list with a binary tree when the number of elements in a bucket reaches certain threshold. While converting the list to binary tree, hashcode is used as a branching variable. If there are two different hashcodes in the same bucket, one is considered bigger and goes to the right of the tree and other one to the left. But when both the hashcodes are equal, HashMap assumes that the keys are comparable, and compares the key to determine the direction so that some order can be maintained. It is a good practice to make the keys of HashMap comparable.
This JDK 8 change applies only to HashMap, LinkedHashMap and ConcurrentHashMap.

[@mahiradolan4160]

Very detailed and excellent explanation. Thank you, Naveen!

[@usmanahmad5448]

This is by far the best explanation.

[@ashuiet]

Earlier I have tried to understand the "Hashing Concept" from several sources but it seems very confusing but the way you have expalain now this concepts has cleared now. So, Here after I can explain the hashing concept to anyone.
Thanks !! Naveen

[@naveenautomationlabs]

Glad that you got the concept. :)

[@hasmukhmaniya4214]

Thanks for the video Naveen and one of the best video to understand HashMap functions.

[@gurunadhmitikela2918]

Wow.. what a wonderful explanation Naveen. Kudos to you for teaching this complex concept in such a simplified way. Really appreciate the hard work you would have put in to break this one brick by brick. :)

[@dhandapani.sudhakar]

Thanks, Naveen for the clear explanation.

[@msanyasirao5411]

Thank you.. Explained in an understanding of this typical hash code topic..Really Good

[@vinodkumar-ss3mb]

What a wonderful explanation sir
You made this topic so easy
God bless you 🙏

[@naveenkumarchowki6717]

Thanks for give the information, I have learned so much...now I can explain got the clarity about how hash map exactly work internally...

[@naveenautomationlabs]

Glad it was helpful!

[@anjalijha1598]

As always best and this specific is really awesome Video on Hashmap internal working .

[@GibyAlex0606]

Thanks Naveeen , this is Awesome explanation

[@sakshiaggarwal6199]

Thanks a lot Naveen. This was much needed to understand the internal working. 😇 Especially the debugging how it is calculating the hashcode is ultimate.

[@Sogdo]

Thanks for the video Naveen, very few content creators covers this topic.

[@tonystark4917]

Best Explanation For Hashmap , Thanks.

[@aryacode1705]

Thank you so much, sir, I can't even imagine how much hard work and research are required to create such knowledgeable content. thanks so much

[@Anuragidiot1]

Great Video finally it helped me understand how it works Thank You Naveen

[@likithahs2469]

really good. Thank you for posting the video. Very well explained

[@sachida23]

Explanation is precise and crisp and well documented thanks for this post.

[@pratikjadhav_6396]

Good way of teaching & explanation Sir.

[@amrendrakumar4280]

theory with practical ,very well explained

[@poonamsharma7026]

Thanks a lot Naveen.
You are right, it really gets difficult to understand from documentation, we need practical implementation, and as always you made it easy :).

[@raghugunda2732]

Very good explanation. Thank you so much

[@vemurisirisha8543]

Superb explanation sir. Thank you so much for all ur efforts!

[@magicallife9299]

Best explanation of hash map

[@vandanamishra6748]

Your each video is so well explained .. after going through your videos my base is getting cleared on many topics .. keep making good videos.. god bless you for ur hard work ..🙏🙏

[@priyanshusinha7056]

Good Explanation ❤❤ Thank you NAVEEN Sir

[@charismatic2]

Thank you so much Naveen for detailed and clear explanation.

[@b3creativevlogs815]

Superb Explanation Naveen now I understood the HashMap how its working...Thank you so much...

[@maheshuma741]

Superb explanation. I have never seen such a clean explanation. Thank you bro. Do more videos on tricky concepts like this

[@sandeepchoudhary3882]

Awesome...very detailed explanation. Thank you Naveen !

[@shilpashravge5393]

Excellent session as usual. Things look so easy after your explanation.
Thanks for the efforts and time 😇

[@sreedevimoningi9739]

Thank you so much Naveen for this video, very detailed and excellent explanation you have given. I did really felt amazing.

[@busijagannathrao2915]

Awesome explanation, but if the hashing explanation is more, like how it's calculating in which node the value will be inserting, then it will be the best-ever i saw in youtube.

[@sathishrajasekar1155]

Thanks Naveen, Useful video.

[@shobhit9826]

Yes this is the most important interview question I have also faced the same multiple times

[@naveenautomationlabs]

yes it is. please prepare it.

[@anupdeshmane8827]

Its awesome easy to understand

[@MrYashMundey]

I will never forget this now. Thank you for making it so easy :)

[@naveenautomationlabs]

My pleasure 😊

[@jugautomation3102]

Amazing Naveen sir... today I got to know what is hashing and hashmap. thank u so muchh sirr.

[@naveenautomationlabs]

Glad that you got the idea about it. Thanks for watching.

[@sumitbabel5415]

Exceptionally well explained , I would really like to express my gratitude for such a marvelous and clear explanation. To be honest I am able to understand and register it very nicely. Many thanks and God bless dear.

[@SarangHoley]

Thanks for the video Naveen, very few content creators covers this topic, and like this till now not available on RUclips 😊👍👍

[@naveenautomationlabs]

Glad you liked it

[@arnavpatil583]

Already cover this topic before 2 years check the links
ruclips.net/video/CojCE-ojdGY/видео.html

[@ankitmahajan8295]

@@arnavpatil583 but naveen's explanation is at different level. he explained it really well.

[@jugautomation3102]

@@ankitmahajan8295 I agre.

[@SarangHoley]

@@ankitmahajan8295 Absolutely correct Ankit, I am completely agree with you.

[@vijayaraghavanvashudevan1977]

Awesome ♥ same index positions for Naveen and Tom. Thank you bro :)

[@naveenautomationlabs]

Glad that you liked it. :)

[@tarunbuser]

Mindblowing

[@gopalpandurangan9768]

Excellent demonstration on HashMap. Thanks

[@shankumondal2881]

Awesome !! It's a very detailed explanation and very interesting . 👍

[@vikasyadav-es8uh]

Thanx for creating this video naveen today only i seen this hashcode and index prectically in deep 😊

[@naveenautomationlabs]

Glad you liked it

[@GyanPrakash-t3d]

Thank you for making this video. Loved your explanation, such an amazing content.

[@himanshikushwah8341]

Best explaination i got so far👍

[@gauravjaykar8126]

Appreciate your Work ,You Covered every Possible concept

[@parameshwarpr1364]

Well explained sir, thank you so much.

[@syedjami4033]

Amazing. Just loved the explanation.

[@Coolharshit149]

What an amazing explanation. Thanks :)

[@anurani7084]

Wonderful and clear explanation 👏👏

[@itzrajani]

Thanks much Naveen for the very detailed explaination.After subscribing to your channel started learning Automation core concepts with confidence. I couldn't even think of my youtube search without this "Naveen automation labs" prefix for Java, python, selenium, design patterns POM, BDD, Github, Jenkin's, concepts, etc, and whatnot.

[@naveenautomationlabs]

Thanks for watching @Rajani :)

[@AbsolutelyAJYoutube]

thanks for creating this video , helped me a lot in understanding this concept.

[@priti436]

Best explanation found 😍

[@kotireddy5272]

Great bro that's amazing explanation and easy to understand

[@MamthaDatta]

Thanks for the video Naveen,Explained very neatly ,super :-)

[@naveenautomationlabs]

You are welcome 😊

[@sujitharavuri3572]

Really appreciate this quality content.Thanks a lot.

[@PravasaBharathiyaTelugodu]

its very good and you have captured all the key points.
keep rocking .. Thanks

[@fathimasifasyedmusthafa9410]

Well Done ... worth watching .. !!

[@badrinathdanave]

Thanks a lot naveen for this great content.

[@mytrading6918]

I think while inserting means put missed one point: at 11.10
The value 4 is the computed index value where the Key will be stored in HashMap. In this case, equals() method check that both Keys are equal or not. If Keys are same, replace the value with the current value. Otherwise, connect this node object to the existing node object through the LinkedList. Hence both Keys will be stored at index 4.

[@Fun_Flicksss]

was very helpful thank you

[@shobhitagarwal9321]

Thanks Naveen, really nice presentation.. 👍

[@SomeshwarPhulari]

Awesome! made me consontrate and understand perfectly. Thanks....

[@panneerselvam.k1613]

Really now only i can able to understand
Thanks Bro

[@chiragpatil9236]

You are awesome sir. Keep up the good work. Thank you😊

[@naveenautomationlabs]

Keep watching, keep learning :)

[@hemanthhemasurya8735]

this was really nice bro..thanks

[@baleeshwarit4207]

Excellent explanation 👌👌

[@varshahiremath1189]

Nicely Explained Naveen

[@nithyarajaram9464]

Very well explained. Thanks a lot

[@tannubajpai4782]

best video Sir
Keep posting Sir