Equals and hashcode contract

What happens when equal objects do not have equal hashcode?
The objects will cause bugs when used with hash-based collections.
All hash based operations will depend on default hashcode implementation that will return unique hashcode for each object - and hence hashmap will not be able to look up keys, hashset will allow duplicates. In this video I demonstrate this.
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[@anuragbharti3773]

Awesome explanation

[@christopherbarrett9900]

Great example. I love when people post examples along with the theory. Good job

[@svalyavasvalyava9867]

clear explanation, thank you!!!

[@varungudisena9463]

very good explanation

[@vikrantkumarsmvdu]

Hi Ranjith, Videos which you have uploaded are very clear to understand. You should upload more videos on different concepts. It will be very helpful to other people.

[@ramc7460]

Awesome explanation I ran out of videos from your channel . We expect many videos from different concepts Great work keep going

[@SuprajaYKM]

very nice explanation

[@MrThanique]

EXCELLENT ONE. Thanks a lot for sharing

[@rohitkarambali779]

sir aap please aur topics pe bhi vdos banaye, its very helpful and knowledgeable for us, u r doing great job

[@amit-vg6cb]

Thanks for posting this video...I have watched many videos on the same concept , but did not get clear idea about this, now I am crystal clear on this topic. Keep posting !!

[@aruntcs2005]

This is awesome stuff..keep up the good work

[@rdayala14]

Pretty neat, simple explanation!! It is always nice to see examples which explains the content. Keep it up!! Looking forward for more topics!!

[@pechorinn]

Very nice explanation. Good job. Thank you!

[@akshoyd7735]

Completely impressed with the content of videos

[@rajeshkolluju2409]

Nice and Simple Explanation..Thank q Sir...

[@misakyanzye4269]

Excellent explanation, clear and concise yeah! thanks

[@janukhandari501]

Very good examples and explanation, hoping to see more videos on topics like threads, spring and more of collections. Thanks

[@shashibhushanthakur1982]

Thanks for this video related to hashCode and equal method

[@pavanscala8957]

It is more helpfull to my Job interview point of view, Thank you very much, This is my first video I SUBSCRIBE Thank you

[@Sk-zs1cw]

Easy to understandable and I learnt so many things about eq & hash contract. Plz make video on Thread, synchronisation and thread executor framework

[@prawinaela]

Excellent video, explained very well

[@praveen2hearts]

Thanks for the video ... Very informative and crystal clear

[@DheerajKumarBarnwal]

Superb explanation and very helpful. Keep up the good work. :)

[@jeffsulman3558]

That was very helpful. Thank you!

[@rashimpathak8117]

Beautifully explained.. do add more video on core java and new java versions

[@jagadishk1173]

Still watching your videos sir it is very useful actually.. Please make more videos..

[@janardhannallapati]

Great videos Ranjith. Please keep posting them.

[@rajeshnarasimha5550]

thank you Ranjith, very useful information & easy to understand..

[@AmitKumar-qh4ow]

Excellent Tutorial Ranjith. Thanks a lot.

[@liferayasif9382]

Thank you so much, awesome tutorial.

[@sinnumunnu]

Amazing Explaination!!

[@srividya157]

Very well explained..

[@coach-okr]

Thank you very much!!! I watched so many tutorials to understand that... Please, make more tutorials

[@aditigoyal2622]

Thanks Ranjith!... i really appreciate this!

[@shank0877]

Great explanation Ranjith. Great job!

[@yoganandraju5539]

Awesome quality bro

[@khursheedbano9046]

Good one..Plz keep posting....

[@sachinbhadrashette3077]

Thank you so much. you explained really very well so that everybody can understand. this is going to help me a lot.

[@ranjithramachandran5928]

practical demonstration of mishaps that can happen if you overlook to implement a good hashcode method and expect equals to work with hash based collection. Questions/Suggestions/Criticisms? please post a comment!

[@tiwarybaba]

Ranjith ramachandran...no criticism, ur videos are good...u explain things very nicely. hope, u'll make some more videos on other topics. 😇

[@Aditya_Valluru]

Bit contradiction : If system generated hashcode is different for two objects which have same attributes, then how new object with same key will replace the old one. HashMap hm = new HashMap(); hm.put(1,"aditya"); hm.put(1,"adityaNew"); s.o.p(hm); prints adityaNew Can you please clarify? Also please post some more videos ... its been long time no see :)

[@subhankarb100]

Thanks !!!! nice explanation...

[@kranti7473]

Pls upload more videos on different java concepts/topics.. Thanks ...

[@nitin8692]

Nice explanation.

[@krishnansblr]

Excellent video Ranjith ramachandran

[@anandprakash3070]

Sir please upload more videos. They are really helpful for us.

[@aniketbharsakale2561]

Making complex look simple. would appreciate if there are more clips on other java topics as well. Thumbs Up. :)

[@iCrazzyShri]

Owesome buddy, Really like your videos. I was expecting you would explain why default hashcode will make your objects unique even if it's values are same and equal method is implemented

[@spujain]

Good explanation..

[@bhushan7546]

Very nice explanation Ranjit Thanks:D I serach alot on Internet for that i did't find such simple solution :D

[@shashisingh7565]

Your videos are quite helpful and you explains concept very well. Plz plz plz make videos on other java concepts like Multithreading, synchronization.

[@ravinasomvanshi6844]

Your videos has some different level as compare to other Java Videos..Thamk u so much.. :) ..Please do a video on Threads in Java and how to avoid dead locks

[@srijitpaul4149]

Nice example.

[@kayeshparvez]

this is because, we have to ensure that "For two equal objects we have to generate same hashcode"

[@siddharthdg]

Please do a video on Threads in Java and how to avoid dead locks .

[@nirmalkumarsahoo8683]

Thanks Ranjith ... could you please upload video which explains how serialaizable interface works

[@PandeyRavindra1]

awesome..

[@dhananjaypatankar6995]

Hello, nice videos. By the way, where are you these days..... Its been a while you have uploaded these videos. I see 2015 videos. Please upload new videos on Java on any concept, there is a learning curve in your videos. I guess, not only me, but many others are also waiting. Thanks.

[@rajasekar8054]

thanks Ranjith !!!

[@akbarsaleem2228]

Thanks Ranjit , it really helpful for me . But one thing i want to know that if we are not implementing hashcode method what internally happening that causes to store duplicate values and not able to get the expected name .

[@lokeshreddy7755]

please do videos on mutithreading thank u ...

[@jackofnotrades15]

Just to add, the key Employeekey class should also be immutable. As it is being used as key in map.

[@SunilKumar-tl6mv]

Nice one on equals-hashcode contract. But my doubt is does hashcode implementation depend internally on equals method? Why would hashcode give different hash values if we override equals method?

[@nikjpr]

thanks!!

[@sahilsehgal626]

Hi Ranjith, Can you please make few videos on multi threading and concurrency in java 5 ?

[@RoopkishorPandeyji]

thanks Ranjith, I got 1 questions in an interview, why hashcode is required, cant only equals method do our job?, If we make our own collection classes, why java wants both equals and hashcode to compare 2 objects.

[@romanlotockijj4806]

Fine... Understood...

[@harishchowdarysure8858]

sir whn u upload thread concurrency.................

[@bhushan7546]

Please upload Java 8 Feature

[@JitendraSingh-zg3ws]

hashset add duplicate elements because internally HashSet use HashMap

[@mishikamehta4610]

Can you provide video on hashtable implementaion?

[@ranjithramachandran5928]

+m mehta , please see kzbin.info/www/bejne/mWS1h4ppgKx8f6c

[@swap000bhosale]

I want to know why are we overriding equals method is it necessary

[@ranjithramachandran5928]

+Swapnil Bhosale - It is necessary when you want to establish equality of your custom Objects. How would you say if your Employee e1 and Employee e2 are same? e1 == e2 check is not sufficient when you establish equality based on fields inside Employee like e1.name, e1.id, etc.

[@harishchowdarysure8858]

plz upload thread Concurrency...................reply me?

[@vicky10ve]

where are you ??? People need you!.. :)

[@harishchowdarysure8858]

sir when u upload thread concurrency?

[@ranjithramachandran5928]

+harish chowdary sure This week.

[@harishchowdarysure8858]

+Ranjith ramachandran Still u doesn't upload Thread Concurrency..............replay me sir...........

[@harishchowdarysure8858]

+Ranjith ramachandran Still u doesn't upload Thread Concurrency..............replay me sir...........

[@ashishkumarsingh1920]

I am fan of your videos sir But your playlist is very limited. Please more possible video make and upload Your teaching style and knowledge in java is so high no compare to you in you tube Thanks sir

[@arpanbanerjee8584]

Why it will causs bugs..you never explained that! Examples were great. But your explanation was not in details Pls explain why it is necessary to override hashcode if we override equals method. How does that work internally if we don t do the same

[@JitendraSingh-zg3ws]

may be you can check out how Hashmap works internally , there is video on this on same channel :)

[@anjaliarorafan6587]

Not intereseted

[@nishaphilip9745]

Hi Ranjith, Videos which you have uploaded are very clear to understand. You should upload more videos on different concepts. It will be very helpful to other people.

[@ashishagrawal7709]

Thank you so much. you explained really very well so that everybody can understand. this is going to help me a lot.

[@ranjithramachandran5928]

+ASHISH AGRAWAL Thanks!

[@harishchowdarysure8858]

sir whn u upload thread concurrency.................