Java interview question on hashcode() and equals() || Java collection interview questions on HASHMAP

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  • เผยแพร่เมื่อ 5 ก.ย. 2024

ความคิดเห็น • 170

  • @SeleniumExpress
    @SeleniumExpress  5 ปีที่แล้ว +7

    For step by step explanation on hashcode and equals() in Java, please check out my new playlist by clicking the link below
    th-cam.com/play/PL3NrzZBjk6m95SR6WzhnOGGCjXZpCoO-k.html

    • @ChongSLee
      @ChongSLee 5 ปีที่แล้ว

      i get invalid parameters... is this right url? thanks.

  • @vimalsubha
    @vimalsubha 6 ปีที่แล้ว +20

    I like the way you started the problem and slowly decoding...

  • @sanketh768
    @sanketh768 2 ปีที่แล้ว +1

    this helped me out with my issue today, thank you ver much

  • @ponsivakumarmanoharan4994
    @ponsivakumarmanoharan4994 3 ปีที่แล้ว

    Good one

  • @shanthinis5667
    @shanthinis5667 ปีที่แล้ว

    Very nice explanation.... Awesome 👍

  • @nareshch6454
    @nareshch6454 3 ปีที่แล้ว

    Wonderful explaination brother

  • @niteshpandey8207
    @niteshpandey8207 ปีที่แล้ว

    That's Amazing I'am not aware about Wrapper class that it having equal and hashcode.

  • @1976balakrishna
    @1976balakrishna 3 ปีที่แล้ว

    nice one

  • @pratikalhat9484
    @pratikalhat9484 2 ปีที่แล้ว

    very nicely explained

  • @user-ln6ij3ko2l
    @user-ln6ij3ko2l หลายเดือนก่อน

    You tooooo have an impeccable knowledge😊😊

  • @sreenivasl5383
    @sreenivasl5383 ปีที่แล้ว

    Explained very nicely.. The way of started, the way of required info from api document, different type objects.. 👏

  • @diavijay08khush94
    @diavijay08khush94 4 ปีที่แล้ว

    I have become fan of you.... thanks for the informative vedio....and for the people it's not the fake accent ... it's his confidence that he gained due to knowledge....so please don't discourage any knowledgeable person like this...

  • @manojdehran4698
    @manojdehran4698 6 ปีที่แล้ว +6

    You are a real coder, otherwise most of the people talks about theory.
    Keep up the good work !!

  • @muralimohan7097
    @muralimohan7097 3 ปีที่แล้ว

    The way you are explaining the concept with example is awesome and it clear to understand

  • @lordgreat6051
    @lordgreat6051 2 ปีที่แล้ว

    Because map uses hash to target keys! brilliant example thanks

  • @AllinOne-et2on
    @AllinOne-et2on 2 ปีที่แล้ว

    I am watching on Sep 2021. Great job bro. ❤️❤️

  • @tasteanotherbite1265
    @tasteanotherbite1265 2 ปีที่แล้ว

    Amazing explanation 👌

  • @PoonamSharma-gy3ky
    @PoonamSharma-gy3ky 2 ปีที่แล้ว

    Really very helpful content with proper explaination

  • @aakashdetwal9950
    @aakashdetwal9950 2 ปีที่แล้ว

    Your way of explain is understandable it is helpful

  • @deepikajagadees7996
    @deepikajagadees7996 2 ปีที่แล้ว

    Thank you a lot for the great explanation

  • @swapnilshinde8110
    @swapnilshinde8110 3 ปีที่แล้ว

    it,s Really Helpful me this video..........Thanks a lot Sir.

  • @mbrajucse
    @mbrajucse 3 ปีที่แล้ว

    Super bro. Nice explaination.👍

  • @sauravsrivastava9019
    @sauravsrivastava9019 2 ปีที่แล้ว

    Good explanation

  • @ElCanalDelPadrino
    @ElCanalDelPadrino 2 ปีที่แล้ว

    Excellent explanation!!

  • @madhavanananthan7077
    @madhavanananthan7077 3 ปีที่แล้ว +1

    Master level explanation, really hats off
    Actually I watched several videos to understand this concept. But this one is 🔥 simply

  • @prashantthite9061
    @prashantthite9061 2 ปีที่แล้ว

    Perfect explanation that I want. Now I am clear with my doubts in hastable. Thanks and please create more video on programming.

  • @letusmeet5427
    @letusmeet5427 4 ปีที่แล้ว

    so super explanation , really it's wonderful explanation. You borned for us only.
    so so sooooo nice of you.. Thank you soooooo much.

  • @sangeethchitravel3092
    @sangeethchitravel3092 4 ปีที่แล้ว

    Good explanation. Addition to that I wanna add one more point, if u add your custom object as key of map then it should be immutable. So u have to make your employee object as immutable object as string class.

  • @dsgtechinfo5639
    @dsgtechinfo5639 3 ปีที่แล้ว

    Thanks a lot friend

  • @kumarvijayag
    @kumarvijayag 2 ปีที่แล้ว

    best example, basic point explained, but still should have talked more about equals and hashcode methods

  • @khagendrakumar8025
    @khagendrakumar8025 6 ปีที่แล้ว

    i saw lots of video but still there is confusion in my mind ,,,after seeing this video i understand 100% of this fundamental,thank u sooooo much,keep going we will support you.

  • @ajaysuresh3781
    @ajaysuresh3781 3 ปีที่แล้ว

    Very nice clear explanation Sir. Thank you 👍

  • @saiadaikappan
    @saiadaikappan 4 ปีที่แล้ว

    Very clear explanation, thank you !!! your voice makes the explanation more interesting.

  • @DavidCervantesmrclutch
    @DavidCervantesmrclutch 3 ปีที่แล้ว

    Nice video Bro

  • @prabudhabansode6953
    @prabudhabansode6953 2 ปีที่แล้ว

    Nicely explained. Thank you!

  • @anonymouskunal2748
    @anonymouskunal2748 3 ปีที่แล้ว

    overall conclusion 10:40 thank you sir

  • @hetalrachh5665
    @hetalrachh5665 4 ปีที่แล้ว

    Amazing and very simple explanation, Thanks !!

  • @subhashininallapati2080
    @subhashininallapati2080 3 ปีที่แล้ว +3

    Excellent teaching. May I know where I can find all your Java interview QA videos, Selenium interview QA , Java tutorial and Selenium tutorial at one place? Could you please share. I am learning a lot from your videos.

  • @danceayush8128
    @danceayush8128 2 ปีที่แล้ว

    Now I actually got the point.. Thanks brother 👍

  • @somethingforyou891
    @somethingforyou891 5 ปีที่แล้ว +1

    Superb explanantion. Thank you

  • @Ishaaninsights
    @Ishaaninsights 6 ปีที่แล้ว +2

    Thank u sir for the great tutorial.This is fundamental and root to start.This is what we missed till now in other tutorials.very unique explanation.Thank u
    ..big fan :)

  • @erictang4447
    @erictang4447 4 ปีที่แล้ว

    Thank you for explanation. The visual animation is very helpful.

  • @saranyan3910
    @saranyan3910 3 ปีที่แล้ว

    Wow! Awesome explanation 🙏

  • @mohanas6697
    @mohanas6697 6 ปีที่แล้ว +17

    Hi, if possible, please explain why we need to override hashcode() if we are overriding equals()...By the way, your accent doesn't matter only subject matters...Keep it going :-) you are doing a great job...

    • @vishalgaikwad873
      @vishalgaikwad873 6 ปีที่แล้ว +3

      Bcz of contract between .equals()/ hashCode() method.
      ->Two equivalent object should be placed in same bucket and There HASHCODE must be same.
      s1.equals(s2); &&
      s1.hashCode()==s2.hashCode();

    • @coolfreaks68
      @coolfreaks68 5 ปีที่แล้ว +3

      I shall add in a few more points after what Gaikwad said .
      • Let's consider we have a HashSet which already has 100 elements preloaded in it.
      • Let's say, we want to add a new element, ie. the 101th element to the set.
      • The HashSet is designed to keep unique elements only. So when the 101th element is introduced, the add() logic will compare the 101th element, with each of the previously stored 100 elements. Right ? This is where hashcode() comes to rescue. If a proper hashcode() logic has been implemented, then the addition of new elements to the HashSet, will require much fewer equality comparisons.
      • For example without hashcode() the add() method has to do 100 equality checks. But with a good hascode() logic, the add() operation may not require more that 20 checks.

    • @srinathravichandran8796
      @srinathravichandran8796 5 ปีที่แล้ว +1

      @@coolfreaks68 Hi subhadeep..I can get ur point that with a good hashcode logic, we can avoid more comparisons.could you pls explain how it minimizes the comparison?

    • @coolfreaks68
      @coolfreaks68 5 ปีที่แล้ว +2

      @@srinathravichandran8796 - Obviously because each Hash bucket usually has fewer elements than its parent Hash Set.
      Only a very bad hascode() logic can push all the elements of HashSet into just one Hash bucket - giving no performance improvement.
      A good hashcode() logic on the other hand, distributes the elements among multiple buckets, with each bucket having very less number of elements and with all the buckets having almost equal number of elements.
      Eg : if you have , lets say a 100 element in hash set.
      A bad hashcode() logic will push all 100 elements into 1 bucket , leaving other buckets empty !
      A good hashcode() logic will push 10 elements to each of the 10 buckets. So whenver you are searching , first you find out the bucket number, then you do a binary search inside that specific bucket. So there is performance improvement.

    • @sergioantoniomartinez9227
      @sergioantoniomartinez9227 4 ปีที่แล้ว

      @@coolfreaks68 that's a clever way of handling buckets, thank you

  • @krishnasingh9111
    @krishnasingh9111 5 ปีที่แล้ว +1

    Very help full for beginners thank you :)

  • @amitaswar7010
    @amitaswar7010 6 ปีที่แล้ว +1

    I like the ending music so much and video too thank you bhai

  • @techsteering
    @techsteering 5 ปีที่แล้ว +1

    Excellent. Thanks for sharing your knowledge.

  • @shubhamraj5184
    @shubhamraj5184 3 ปีที่แล้ว

    Wow thanks 💓

  • @mayerbeats6754
    @mayerbeats6754 6 ปีที่แล้ว +3

    Спасибо! Thank you from Russia!

  • @trendytopics-
    @trendytopics- 2 ปีที่แล้ว

    THANK YOU SO MUCH!

  • @macherladevasundaram4928
    @macherladevasundaram4928 4 ปีที่แล้ว

    Very good explanation bro.. Thank you..

  • @priyankaraut9289
    @priyankaraut9289 4 ปีที่แล้ว

    Gud information keep going

  • @shalabhdixit
    @shalabhdixit 5 ปีที่แล้ว +10

    No where the difference between hashCode and equals is explained. Also please explain why we need to generate the hashcode and equals method and how did it make the values change from 2 to 1

    • @SeleniumExpress
      @SeleniumExpress  5 ปีที่แล้ว +2

      Hi Shalabh,
      This is a video from my interview questions and answers series. So I haven't covered the concept in this video rather this is just an interview question that I am trying to explain. I will be posting a complete video on this concept in the coming week.

    • @shalabhdixit
      @shalabhdixit 5 ปีที่แล้ว

      @@SeleniumExpress ok. Thank you!

    • @merajulhaque9107
      @merajulhaque9107 4 ปีที่แล้ว

      @@SeleniumExpress Can you please share the link for the complete concept video.

  • @salenaluu8477
    @salenaluu8477 3 ปีที่แล้ว +1

    Thank you so much

  • @OrdinaryTalesofSamriddhi
    @OrdinaryTalesofSamriddhi 3 ปีที่แล้ว

    You describe everything in such an organized and nice manner. No one can compete you. From covering the most trivial detail to covering the complex thing of every concept is what makes you unique. Keep up the good work. Looking forward to many more informative videos from you.

  • @chloeren9175
    @chloeren9175 2 ปีที่แล้ว

    Thank you so much for your great explanations! so all i need to do is to go to Id=>source=>generate hashcode( )and equal(),so i cn get the map.size(1),right?

  • @AtulMishra-rs5os
    @AtulMishra-rs5os 6 ปีที่แล้ว +18

    Explanation was helpful but a bit confusing during few moments. Two advice for you if you accept it.... First: Try to speak in Indian accent of English so it won't fake. Second: Reduce the redundancy of some words you speak very frequently i.e. 'Over here'. You don't complete your most of the sentences without prefixing or suffixing 'Over here' ;). Please don't take it personal and also remember "Your critics are your biggest followers".

    • @rajeshchouhan458
      @rajeshchouhan458 5 ปีที่แล้ว

      Agreed men

    • @SudhanshuSrivastavaIndia
      @SudhanshuSrivastavaIndia 5 ปีที่แล้ว +1

      I have same opinion. Sometimes it made me feel annoying.
      Fantastic tutorial but need to improve the above mentioned points.

    • @august24outing5
      @august24outing5 4 ปีที่แล้ว

      Agree, that's the worst part of it...be natural...

  • @abhinavghosh725
    @abhinavghosh725 4 ปีที่แล้ว +2

    finally someone clearly explained it!

  • @harit9380
    @harit9380 4 ปีที่แล้ว

    Great Video!! Understood clearly!

  • @atiqulny
    @atiqulny 4 ปีที่แล้ว

    You are a genius

  • @gauravsharma875
    @gauravsharma875 3 ปีที่แล้ว +1

    How come emp1 and emp2 having the same hashcode? Can someone please help

  • @RiyazParasara
    @RiyazParasara 5 ปีที่แล้ว +1

    Great thanks.

  • @sulavagarwal3561
    @sulavagarwal3561 6 ปีที่แล้ว +1

    u got great explanation skills

  • @ShubhamGupta-fm7lv
    @ShubhamGupta-fm7lv 6 ปีที่แล้ว +10

    I don't know why I didn't see this video earlier. Got this in an interview and I wasn't able to answer.

  • @srilakshmi5922
    @srilakshmi5922 4 ปีที่แล้ว

    simply awesome

  • @srikanth29
    @srikanth29 6 ปีที่แล้ว +1

    Thank u very much. Very helpful and clear

  • @lux27.42
    @lux27.42 5 ปีที่แล้ว

    this video easy to understand :) thankyou so much.

  • @JaishriVemuganti
    @JaishriVemuganti ปีที่แล้ว

    I put the code as you shown in my side and in both cases ham getting size =2

  • @harshav3902
    @harshav3902 4 ปีที่แล้ว

    Thanks for the explanation dude. It helped.

  • @srinivasang4566
    @srinivasang4566 5 ปีที่แล้ว

    Nice

  • @premkirankatinedi4479
    @premkirankatinedi4479 5 ปีที่แล้ว

    Wow...this is to the point. Thanks a lot

  • @kanagarathinamannamalai8020
    @kanagarathinamannamalai8020 5 ปีที่แล้ว

    Nice Explanation bro.Thanks👍..

  • @priyankaraut9289
    @priyankaraut9289 4 ปีที่แล้ว

    Do videos on java framework

  • @ARI-em6me
    @ARI-em6me 5 ปีที่แล้ว

    Very very clear explanation. Plse upload how to upload webproject deployed server

  • @kingajable
    @kingajable 4 ปีที่แล้ว

    you doing great job buddy keep it up

  • @alittlecoding
    @alittlecoding 5 ปีที่แล้ว

    Good job. thanks

  • @kssinfonet2394
    @kssinfonet2394 2 ปีที่แล้ว

    Dear Abhilash sir i have one que. which empoyee object will hashmap put 1st ya 2nd after using hashmap and equal method😊

  • @rameshbabu5754
    @rameshbabu5754 4 ปีที่แล้ว

    Below my all question are more help full in interview point of view.
    So, Could you please explain below all videos to me

  • @helishah9065
    @helishah9065 5 ปีที่แล้ว +1

    Amazing explanation! Thanks a lot :)

  • @damodaranm3044
    @damodaranm3044 4 ปีที่แล้ว

    Wow r Ally good .and why don't you make videos in following concept cuz there is no good videos in TH-cam threads collection jsf spring

  • @tw5529
    @tw5529 3 ปีที่แล้ว

    Great Explanation👌 Thanks a Lot :-) . BTW, which software are you using for making this video?? It looks so attractive 😊

  • @rthiaga
    @rthiaga 5 ปีที่แล้ว +1

    In the hashCode method why 31 is multiplied by 1 and id. We can directly return the id right?

    • @raghavanaliassaravananm1546
      @raghavanaliassaravananm1546 5 ปีที่แล้ว +2

      No. That is really required for Hashing, which recommends the key value (here 'id') to be multiplied by a prime number. For all sake of randomness. Most people take 31 as a good prime number to have a better sampling.

  • @krishnasuripaka2480
    @krishnasuripaka2480 4 ปีที่แล้ว

    Super Brother...

  • @felixkimutai8478
    @felixkimutai8478 5 ปีที่แล้ว

    Great! Thank you.

  • @trendingtechnologiesit924
    @trendingtechnologiesit924 6 ปีที่แล้ว

    Simply awesome

  • @start1learn-n171
    @start1learn-n171 2 ปีที่แล้ว

    TQ

  • @premkirankatinedi4479
    @premkirankatinedi4479 5 ปีที่แล้ว

    Simply Awesome!!

  • @subramanianchenniappan4059
    @subramanianchenniappan4059 5 ปีที่แล้ว

    Thanks a lot

  • @sonyguptayourdearestsony
    @sonyguptayourdearestsony 5 ปีที่แล้ว

    nice good explanation

  • @aishwaryarokade1150
    @aishwaryarokade1150 5 ปีที่แล้ว

    Thank you

  • @bakhromachilov8456
    @bakhromachilov8456 4 ปีที่แล้ว

    Perfect

  • @rameshbabu5754
    @rameshbabu5754 4 ปีที่แล้ว

    Could you please explain the Internal mechanism of HashSet in java with theory and real time examples

  • @rameshbabu5754
    @rameshbabu5754 4 ปีที่แล้ว

    Could you please explain the oops (Abstraction, Inheritance, Encapsulation, Polymorphism ) concepts in java with theory and real examples

  • @himachaliravi
    @himachaliravi 6 ปีที่แล้ว

    Good example

  • @rameshbabu5754
    @rameshbabu5754 4 ปีที่แล้ว

    Could you please explain the use of Comparable and Comparator in java with theory and real time examples

    • @dhanalaxmi2569
      @dhanalaxmi2569 4 ปีที่แล้ว

      Verify durga software videos it is explained thr

  • @aayush-zw1mx
    @aayush-zw1mx 3 ปีที่แล้ว

    But Sir the two employees object hold different memory addresses and in a map we cannot have same keys and in this case the keys emp1 and emp2 are already different only the value they contain are same .So how are the entry set duplicates.Can you pls explain

  • @commonman8540
    @commonman8540 2 ปีที่แล้ว

    HI Avinash, When we use jpa repository.saveOrUpdate(product);, my product object has 1 lak records, will it accept? Is there any limitation ?

  • @rameshgollapudi588
    @rameshgollapudi588 6 ปีที่แล้ว

    Very nice

  • @deepar781
    @deepar781 5 ปีที่แล้ว +1

    Its good. Keep Posting bro

  • @digvijaynegi6917
    @digvijaynegi6917 5 ปีที่แล้ว

    Thanks