Java collections framework interview questions and Answers | MOST ASKED | Core Java | Code Decode

[@shubhamtagalpallewar7125]

It helped me in my interview preparation.. thanks

[@CodeDecode]

Hope you get all your interviews cleared. All the the best 🤟

[@suratdas3866]

@@CodeDecode aa

[@realnileshpawar]

Kuthe rahto bhau tu? Do u want to take live instructor led classes? I have over 5 years of experience in corporate.

[@accforgame8563]

​@@realnileshpawar how do i contact u?.

[@dubeyankitsarar8084]

Yes

[@kirushnashirre6791]

Though I knew about the framework completely, I had an issue explaining it in an organized way, you are just awesome!

[@CodeDecode]

Thanks 👍

[@rohanbhargava3953]

Great video! One addition to the last question on implementation of HashMap
Since Java 8, once a threshold limit is reached for the number of linked list elements added at a particular node, the linked list is re-ordered to a binary tree to implement faster search for collision cases.

[@CodeDecode]

Thanks for the info

[@JenilCalcuttawala]

Binary but Binary Search Tree right?

[@JustOssetian]

​@@JenilCalcuttawala red black tree

[@kathiravanjagadeesan]

Beautiful Effort.IT Field will remember your name forever.

[@CodeDecode]

Thanks for wonderful comment kathiravan. you might not know this but you made our day and all the efforts we did now turned meaningful bcz of such nice words🙏🙏. We , team code decode is grateful 🙏🙏. keep learning Kathiravan, you will surely land at your dream place really soon. all the best 👍👍👍👍

[@GaneshSingh1]

I have read theory before but confused after this video cleared all doubts about Hashmap,, thanks a lot

[@CodeDecode]

We are glad to know that this helps Ganesh 🙏👍

[@coincidentIndia]

SortedSet uses Comparator(Comparator

[@robelhailab394]

Great Explanation!!!
One more point: Hashtable doesn’t extend Hashmap.
It extends Dictionary Class.

[@CodeDecode]

👍👍

[@pallavipatare2004]

This is my first ever TH-cam comment. I just logged in to youtube so that I can comment on your video.
You are awesome. Very well explained, very well organised. Keep it up. No nonsense videos. I am preparing for my interviews using your videos only. Pls countinue uploading many such videos.

[@CodeDecode]

Thanks Pallavi 🙂👍

[@prakashkaruppusamy3817]

This is a awesome 'Ready Reckoner'. I watched this and all are explained clear and to the point. This is great effort by the creator. Please make more topics and please make more videos. I totally understood the points. All the very best team 👍👏
With Regards,
Prakash Karuppusamy

[@CodeDecode]

Thanks for the nice words Prakash. We will sure make more videos like this ....

[@robinbhargava111]

Very informative and quick to brush up collection framework with examples.

[@CodeDecode]

Thanks Robin 🙂👍

[@dasarajusaikumar8585]

your phone vibrates in almost all of your videos. thats very nice :-). it's not a complaint, take it as a compliment

[@CodeDecode]

we fixed this issue in new videos. Thanks 👍👍😊😊

[@farrukhahmedsid]

how this can be a compliment? :D

[@sharath.rajesh]

Hi Mam, this video about collections helped me during my interview with TCS and I secured a job offer!
Thank you very much and I will continue to look through your other videos to help broaden my knowledge

[@venkatv3690]

Best i have seen before the way ur explaining very well thank you

[@CodeDecode]

you're welcome venkat

[@Athira_Surendran]

The way you explaining each topic is awesome.
Thank you for the amazing video.

[@CodeDecode]

Thanks for the nice words.....

[@agnesmarygreeshma607]

How many interviews I've cleared listening to this video ! Thank u :)

[@CodeDecode]

Many many congratulations on clearing your interviews!! Keep learning keep shining 🌟🌟

[@JourneyswithAK]

Seriously very great explanation ❤️

[@CodeDecode]

Thanks a lot 🙂🙂👍👍

[@mitra.1]

Thanks a lot.. The best Collection summary available on YT.

[@jasper5016]

It enhanced my knowledge for sure. Thanks.

[@anshumanpanigrahi7817]

Ma'am, thank you for this.
It really helped me in cracking Amdocs. I was able to recall the exact same thing you taught in this video.
I can say, that I've done DSA and used every framework that's why it looked very understandable at the very first go.

[@CodeDecode]

Congratulations Anshuman 🎊🎊🎉🎉

[@moneymastermind-w7c]

HI Anshuman , Bro i have an Amdocs interview in upcomming week. Can u pls help me in that like how is the interview and what questions were asked in that interview please ? Can we connect?

[@anshumanpanigrahi7817]

@@moneymastermind-w7c Topics- Java, Oops, Threads, Collections, SQL, DBMS, Unix commands, 2 programming questions. Go through interview experiences from gfg & Coding Ninjas/CodeStudio, that'll be enough.
Mine was for developer profile.

[@moneymastermind-w7c]

@@anshumanpanigrahi7817 Thanks a lot for reply bro. Mine interview is also for developer role 2 years of experience. May i know what type of programming questions were asked in interview ?

[@shivaniagrawal4473]

Thank u so much,your way of explaining concepts are wonderful.I am feeling so confident in Java after watching your interview questions.

[@CodeDecode]

Thanks Shivani 👍👍. Keep learning keep shining ⭐✨⭐✨

[@vinodkumar-lq7oo]

Really very good explanation.
We are lucky to watch this.

[@CodeDecode]

Thanks Vinod 👍

[@savitarohra3905]

Everything explained to the point!! Thank you for making great videos

[@CodeDecode]

Thanks Savita 👍

[@sivasankarbestha]

Very clear explanation.. and provide example code 👍👍👍👍

[@CodeDecode]

Thanks Siva 👍👍

[@rishiraj2548]

5 lakh 48 thousand + views
Congrats 🎉🎉🎉

[@CodeDecode]

Thanks Rishi for your constant support

[@nagavenkatakishore4109]

Nice explanation friend thank you very much for sharing.

[@CodeDecode]

Thanks for the nice words 👍

[@satishdhaigude629]

Thank you, nice explanation of all collections, mostly I like internal working of hash map, got the more clarity….

[@CodeDecode]

th-cam.com/video/7k0VYHuUF6g/w-d-xo.html

[@nikhleshagrawal]

from Java 8, the linked lists are dynamically replaced with balanced binary search trees in collision resolution after the number of collisions in a given bucket location exceed a certain threshold.
This change offers a performance boost, since, in the case of a collision, storage and retrieval happen in O(log n).

[@CodeDecode]

Yes we have covered that in latest videos I. E. top interview questions 👍👍. Thanks

[@jakubdudek4133]

For others who are interested in that particular topic, the threshold by default is 8 as far as I remember. :) So "after" 8 nodes, LinkedList is being switched to Tree Balance Structure.

[@kajalkukreja694]

Very good questions and their detailed explanation. Thanks 👍👍

[@CodeDecode]

Thanks for the nice words...

[@rishiraj2548]

16:07
ConcurrentModificationException:-
When modification is performed on a collection by the same thread which is iterating over that collection.
It's not about two distinct threads for iterating and modifying.

[@shubhamshende9995]

very clear and crisp explaination 💥

[@CodeDecode]

Thanks Shubham 🙂👍

[@RaviK-lv9zf]

Beautiful voice.. 😅 and the content is so good that you almost covered main topics that can consume most of the time at institutes.

[@CodeDecode]

Thanks Ravi 🙂🙂

[@gurudassulebhavikar]

In case of hash collision it also uses equals method to check if key is same. If it is same then it updates the value. Otherwise, new node is inserted.

[@praveenpatel3957]

This special video covered all related to collection and its interview questions have watched so many videos about that but here have learnt in very different way thanks for sharing such valuable content in the video keep sharing like this we get to learn more..❤❤

[@arifpari9561]

You just nailed the Collections . One small request please do video on Collections on Java 8 prospective.

[@CodeDecode]

Sure will make a seperate video on Java 8 specific changes

[@kamallochannayak2706]

Thank you mam .....your way of talking/understanding.....love it

[@CodeDecode]

You're welcome kamal.....

[@kamallochannayak2706]

❤

[@ronyuniverse]

Good one mam,please continue such videos.

[@CodeDecode]

sure we will upload more

[@vinayvjs628]

Best study video for interview

[@CodeDecode]

Thanks 👍👍

[@deviprasadhota2617]

Nice work...one mistake is map interface doesnt extends(not implement) Collection interface

[@solomonrajkumar5537]

Hats off very nicely explained and your presentation is also too good.

[@CodeDecode]

Thanks 👍

[@sagarmane3291]

Superbbb...! your explanation skills are just awesome....
and ur voice is adorable as well. thanks for this questions set it will be really helpful

[@CodeDecode]

Thanks Sagar 🙂🙂

[@kemparaj565]

Very good. Explanation. Thank You 😊

[@CodeDecode]

Thanks 🙏

[@farrukhahmedsid]

Yes this is literally most asked and top questions. Thanks.

[@CodeDecode]

Thanks

[@chishamalama]

Thank you once again for explaiing clearly

[@CodeDecode]

Thanks Chisha Malama 🙂🙂👍👍

[@sneharaghuwanshi4933]

Hello Ma'am, I have learnt a lot from your channel thank you so much. I have one doubt here that the linked list does not support index based search but it has a get method through which the element is at a specific position?

[@SuperMilanjain]

Really a nice approach to make understand the topic. Just one request, plz add some behavioral questions related to collection as interviewer can ask that also.

[@TheFebruary10]

Very good to remember and recollect

[@CodeDecode]

Thanks Sanjeev 🙂👍

[@satishr2071]

Nice video keep it up 👍

[@CodeDecode]

Thanks ☺️

[@sekhar14301]

Thanks for wonderful explanation 🤝

[@CodeDecode]

You are welcome

[@sureshgarine]

Thank you so much, madam. You explained in-depth and very nicely

[@CodeDecode]

Thanks 👍👍

[@kp-ps7wi]

Explanation is awesome. Just a suggestion. In the diagram just put dotted line for interface and solid line for class. So while seeing the diagram people will understand the concept.

[@CodeDecode]

That's a very nice suggestion. Thanks 🙏👍👍👍👍

[@tusharkawade1937]

4:42 small correction, I think Linkedlist do allow index base search

[@kazaasekhar]

very nice but need more questions from collections with demonistration

[@CodeDecode]

Sure we will create soon

[@mohammedabraruddin9779]

yes i would love to see internal working of hashSet

[@CodeDecode]

th-cam.com/video/7k0VYHuUF6g/w-d-xo.html

[@shubhammowade.6019]

Respect for your explanation ma'am...

[@CodeDecode]

Thanks 👍

[@WondersOfWandering]

Excellent videos, Thank you so much!

[@CodeDecode]

Thanks Nidhi 🙂👍

[@bhavyabhardwaj4563]

Very good explanation of Internal working of hashmap. Liked it.

[@CodeDecode]

Thanks

[@rajatram5068]

Awesome Explanation

[@CodeDecode]

Thanks......

[@sushmakolli1119]

Please make another video(part2)on collections tricky questions and include concepts like internal working of hash set

[@CodeDecode]

th-cam.com/play/PLyHJZXNdCXsfqAkteaQ6JfZ_IHvxX-Hj3.html

[@sreejak6776]

Pleasr create more tricky questions on collections

[@CodeDecode]

sure sreeja we will create soon

[@Hare_Krishna143]

Such helpful content and appreciate your hardwork Thank you mam!!

[@CodeDecode]

Thanks Manoj 🙂👍

[@BhushanRawoolShridhar]

Nice explanation,you are doing a great job. Thank You

[@CodeDecode]

Thanks Bhushan 👍👍

[@ammarzafar1337]

Very Well Explained.

[@CodeDecode]

Thanks Ammar 🙂👍

[@RickyYadav_at_googleplus]

very nicely explained... eagerly waiting for Multi-threading concepts.. once again good job!

[@CodeDecode]

Thanks .......

[@Sakshi-gs5tl]

Awesome video for java collections 💯💯💯

[@CodeDecode]

Thanks sakshi 👍

[@sourabhjinde8191]

Thanks.. that was awesome 👍

[@CodeDecode]

Thanks Sourabh 🙂👍

[@arunkumarmn7493]

Wow great explaination

[@CodeDecode]

Thanks 👍

[@SravanKumarG-ty7bz]

Hi,As you mentioned, Hashset simply implements Hashtable. It means Hashtable is an interface. But hashtable is class, right? Can you please comment on this?

[@CodeDecode]

" Implemented " by this i didn't mean inheritance . I meant how we code it. It means in real time we implement set using hash table. Means it's backed by hash map/ hash table . Sorry for your confusion. Implemented is a term used in both English language and in technical terms

[@danilozimermann7809]

Very well explained! thank you

[@CodeDecode]

Thanks 👍👍

[@realnileshpawar]

Gem 💎 👌👌👌👌👌

[@CodeDecode]

Thanks Nilesh 🙂🙂👍👍

[@shamilraj322]

Thank you for a very detailed explanation. :) Expecting more videos like this.

[@CodeDecode]

Sure Shamil. We will upload more videos on collection framework

[@venkatkancharla984]

thanks for all the tricky quaetions, please explain the HashMap with some examples and this is very short. because i was understanding this only theoretically but havent't implemented. bit more explanation on hash map.. it also talks about the equals() and hashCode() contract..

[@CodeDecode]

Hi Venkat
These are only interview questions. Will create tutorial for this very soon 👍👍

[@venkatkancharla984]

@@CodeDecode sure, thanks

[@AK-tt7fc]

the video is very usefull . at 3.40 you interchangeably used implements and extends keyword . if possible correct that .

[@sailakshmantech55]

thank you madem very good explanation 👌👌👌🙏

[@CodeDecode]

You are welcome

[@PKS-ky9se]

Thanks for the great video. Helped me a lot.

[@CodeDecode]

You're welcome

[@praveenagrawal9616]

Thanks for the video. It's really helpful for interview preparation. One small doubt I have in 6:57 you said hashset internally implements hashtable and one null value can contain. But hashtable doesn't contain any null key and null value.. Please explain and correct me.

[@kshitijnimkar4252]

Content is really usefull mam! If possible can you attach ppt document also with the video. It would help for quick recap

[@aurawithrav]

Thank you so much , I found all my interviews questions from there...We need people like you!

[@CodeDecode]

Thanks for nice words chandan

[@piyushrayrikar]

Good content

[@CodeDecode]

Thanks 👍👍

[@robelhailab394]

You are awesome, thanks for thanking your time to help us on interview preparations!

[@CodeDecode]

Thanks for motivating us to put more efforts for community 🙂. We are glad to do that 🙂👍

[@venkatasaikrishnak6984]

Please continue and create video for internal working of hashset as well.

[@CodeDecode]

Sure👍👍

[@cab0620]

With this quality of content, you can create a course in coursera / udemy also

[@CodeDecode]

🙂🙂

[@shashanksharma7747]

Good video

[@CodeDecode]

Thanks

[@kaushikigoel759]

Each and every video is so informative!! Love your content ❤️..

[@CodeDecode]

thanks kaushiki

[@amitarcade]

For hashmap internal working, hashcode method is called by hash method of HashMap and hash method calculates index based on hashcode value

[@CodeDecode]

th-cam.com/video/7k0VYHuUF6g/w-d-xo.html

[@taheershaikh9184]

OMG this is really what java developers are looking for

[@harshadakankhar4875]

Please make a video for Spring interview questions as well..

[@CodeDecode]

Sure will do that soon

[@harshadakankhar4875]

Code Decode anyway the way you explain is just wow 🤗🤗

[@CodeDecode]

thanks :) 👍

[@dungeonmaster2844]

Awesome !!

[@CodeDecode]

Thanks

[@sriharini8309]

Very nice one. CAN you also please elaborate on live examples on each collection class. That's wud help us a lot

[@CodeDecode]

Sure Anupama 👍👍

[@sriharini8309]

@@CodeDecode Thaks much for the reply. Please make a video on recat and angula part also.

[@Priya1_123]

Quite useful info👍

[@CodeDecode]

Thanks 🙏

[@kanhashukla6265]

nicely done

[@CodeDecode]

Thanks!

[@neerajkbc]

Thanks for the video, really helpful 👍

[@CodeDecode]

You are welcome neeraj...

[@ankush_in_sync5998]

Thank you. Keep it up.

[@CodeDecode]

You're welcome ankush

[@joyateechattopadhyay9510]

Very nicely explained ..

[@CodeDecode]

Thanks

[@alexandr7686]

You forgot top interface Iterable, please update collection hierarchy if possible or add comment. Thanks for video, waiting for next!

[@gokulaher2476]

Question: If the key of Hashmap is Immutable Object(properly create by developer with no mistake or let's say it's String class object) then do we need to override hashcode() and equals()? Or having immutable field as key solves the problem of overriding hashcode() and equals()?

[@CodeDecode]

Yes you have to.

[@CodeDecode]

Immutability does not make sure that your equal objects are stored at same bucket location. Hash code does. Interviewer is just trying to trick you.

[@gokulaher2476]

@@CodeDecode thank you!

[@koteshwarvenigalla7150]

Great explanation!

[@CodeDecode]

Thanks..

[@suvadipghosh1385]

18:44 Madam i think you are referring to Hashtable(thread-safe).....But by mistake it's written HashMap in this note.

[@dipabhow4630]

so nice love it

[@CodeDecode]

Thanks 🙂👍

[@narendulatharun9624]

Wow great mam thanks for this amazing video🔥

[@CodeDecode]

👍👍

[@sanjeetkrsinha]

Your video helps me a lot for preparation of interview. Do you have any the text tutorial also for it?