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

[@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 🙂👍

[@robelhailab394]

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

[@CodeDecode]

👍👍

[@pallavipatare2004]

This is my first ever RUclips 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 🙂👍

[@mitra.1]

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

[@venkatv3690]

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

[@CodeDecode]

you're welcome venkat

[@jasper5016]

It enhanced my knowledge for sure. Thanks.

[@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.

[@sharathrajesh9494]

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

[@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

[@JourneyswithAK]

Seriously very great explanation ❤️

[@CodeDecode]

Thanks a lot 🙂🙂👍👍

[@savitarohra3905]

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

[@CodeDecode]

Thanks Savita 👍

[@Athira_Surendran]

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

[@CodeDecode]

Thanks for the nice words.....

[@vinodkumar-lq7oo]

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

[@CodeDecode]

Thanks Vinod 👍

[@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 ⭐✨⭐✨

[@satishdhaigude629]

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

[@CodeDecode]

ruclips.net/video/7k0VYHuUF6g/видео.html

[@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 🙂🙂

[@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..❤❤

[@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

[@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.

[@farrukhahmedsid]

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

[@CodeDecode]

Thanks

[@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

[@solomonrajkumar5537]

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

[@CodeDecode]

Thanks 👍

[@kamallochannayak2706]

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

[@CodeDecode]

You're welcome kamal.....

[@kamallochannayak2706]

❤

[@shubhamshende9995]

very clear and crisp explaination 💥

[@CodeDecode]

Thanks Shubham 🙂👍

[@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.

[@kajalkukreja694]

Very good questions and their detailed explanation. Thanks 👍👍

[@CodeDecode]

Thanks for the nice words...

[@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 🎊🎊🎉🎉

[@shouryapradhan184]

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]

@@shouryapradhan184 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.

[@shouryapradhan184]

@@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 ?

[@nagavenkatakishore4109]

Nice explanation friend thank you very much for sharing.

[@CodeDecode]

Thanks for the nice words 👍

[@bhavyabhardwaj4563]

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

[@CodeDecode]

Thanks

[@kemparaj565]

Very good. Explanation. Thank You 😊

[@CodeDecode]

Thanks 🙏

[@ronyuniverse]

Good one mam,please continue such videos.

[@CodeDecode]

sure we will upload more

[@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 🙂🙂

[@Hare_Krishna143]

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

[@CodeDecode]

Thanks Manoj 🙂👍

[@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.

[@kazaasekhar]

very nice but need more questions from collections with demonistration

[@CodeDecode]

Sure we will create soon

[@chishamalama]

Thank you once again for explaiing clearly

[@CodeDecode]

Thanks Chisha Malama 🙂🙂👍👍

[@WondersOfWandering]

Excellent videos, Thank you so much!

[@CodeDecode]

Thanks Nidhi 🙂👍

[@sekhar14301]

Thanks for wonderful explanation 🤝

[@CodeDecode]

You are welcome

[@shamilraj322]

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

[@CodeDecode]

Sure Shamil. We will upload more videos on collection framework

[@seethegodinyou]

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

[@CodeDecode]

Thanks for nice words chandan

[@deviprasadhota2617]

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

[@BhushanRawoolShridhar]

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

[@CodeDecode]

Thanks Bhushan 👍👍

[@Sakshi-gs5tl]

Awesome video for java collections 💯💯💯

[@CodeDecode]

Thanks sakshi 👍

[@tusharkawade1937]

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

[@kaushikigoel759]

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

[@CodeDecode]

thanks kaushiki

[@sureshgarine]

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

[@CodeDecode]

Thanks 👍👍

[@ammarzafar1337]

Very Well Explained.

[@CodeDecode]

Thanks Ammar 🙂👍

[@sailakshmantech55]

thank you madem very good explanation 👌👌👌🙏

[@CodeDecode]

You are welcome

[@RickyYadav_at_googleplus]

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

[@CodeDecode]

Thanks .......

[@shubhammowade.6019]

Respect for your explanation ma'am...

[@CodeDecode]

Thanks 👍

[@sreejak6776]

Pleasr create more tricky questions on collections

[@CodeDecode]

sure sreeja we will create soon

[@vinayvjs628]

Best study video for interview

[@CodeDecode]

Thanks 👍👍

[@sushmakolli1119]

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

[@CodeDecode]

ruclips.net/p/PLyHJZXNdCXsfqAkteaQ6JfZ_IHvxX-Hj3

[@TheFebruary10]

Very good to remember and recollect

[@CodeDecode]

Thanks Sanjeev 🙂👍

[@mohammedabraruddin9779]

yes i would love to see internal working of hashSet

[@CodeDecode]

ruclips.net/video/7k0VYHuUF6g/видео.html

[@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 🙂👍

[@PKS-ky9se]

Thanks for the great video. Helped me a lot.

[@CodeDecode]

You're welcome

[@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 :) 👍

[@rajatram5068]

Awesome Explanation

[@CodeDecode]

Thanks......

[@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?

[@danilozimermann7809]

Very well explained! thank you

[@CodeDecode]

Thanks 👍👍

[@neerajkbc]

Thanks for the video, really helpful 👍

[@CodeDecode]

You are welcome neeraj...

[@sourabhjinde8191]

Thanks.. that was awesome 👍

[@CodeDecode]

Thanks Sourabh 🙂👍

[@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

[@satishr2071]

Nice video keep it up 👍

[@CodeDecode]

Thanks ☺️

[@kshitijnimkar4252]

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

[@venkatasaikrishnak6984]

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

[@CodeDecode]

Sure👍👍

[@arunkumarmn7493]

Wow great explaination

[@CodeDecode]

Thanks 👍

[@taheershaikh9184]

OMG this is really what java developers are looking for

[@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 🙏👍👍👍👍

[@realnileshpawar]

Gem 💎 👌👌👌👌👌

[@CodeDecode]

Thanks Nilesh 🙂🙂👍👍

[@joyateechattopadhyay9510]

Very nicely explained ..

[@CodeDecode]

Thanks

[@AK-tt7fc]

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

[@narendulatharun9624]

Wow great mam thanks for this amazing video🔥

[@CodeDecode]

👍👍

[@ankush_in_sync5998]

Thank you. Keep it up.

[@CodeDecode]

You're welcome ankush

[@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.

[@jeevansaimanikanta782]

Thanks . Please do the video showing the internal implementation of HashSet as well and also tell the info like in which scenario which kind of Collection is the suitable one to use

[@CodeDecode]

Nice topic thanks 👍

[@amitarcade]

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

[@CodeDecode]

ruclips.net/video/7k0VYHuUF6g/видео.html

[@dipabhow4630]

so nice love it

[@CodeDecode]

Thanks 🙂👍

[@debasishpanigrahi4503]

6:50 Hashtable isn't implemented Hashset, it's "Hash Table" in the code of Hashmap. please check and correct.
I got confused when I watched first.
If i interpreted wrongly, Please let me know your thoughts.

[@CodeDecode]

Internally hash map uses hash table. Hash set internally uses hash map. So indirectly hash set uses hash table .

[@Priya1_123]

Quite useful info👍

[@CodeDecode]

Thanks 🙏

[@alexandr7686]

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

[@vipinahuja6096]

Thanks for the awesome video. However, 18:40 you mentioned HashMap is slower as compared to its respective concurrent counterparts. But that's not true as HashMap is non-synchronized faster. Please correct me if I am wrong

[@ravikaramunge8028]

Thanks its really helpful 😊

[@CodeDecode]

We are glad it's helpful. Thanks for writing back Ravi 👍

[@parulanand7902]

Thank you for the amazing video.. It helped me a lot for my interview.

[@CodeDecode]

Thanks for writing back to us Parul . We hope u land at your dream job soon. All the very best from team code decode, for your interviews. Keep learning keep growing.

[@shashanksharma7747]

Good video

[@CodeDecode]

Thanks

[@koteshwarvenigalla7150]

Great explanation!

[@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.

[@piyushrayrikar]

Good content

[@CodeDecode]

Thanks 👍👍

[@dungeonmaster2844]

Awesome !!

[@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

[@DiKshu33]

@codedecode NavigableSet & NavigableMap interfaces are missed