Equals and Hashcode Contract in Java [Important Java Interview Question] | Code Decode

In this video of code decode we have covered Equals and hashcode contract || Equals and hashcode in Java

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How equals and hashcode contract works in java ?

The default implementation is not enough to satisfy business needs, especially if we're talking about a huge application that considers two objects as equal when some business fact happens. In some business scenarios, developers provide their own implementation in order to force their own equality mechanism regardless the memory addresses.

As per the Java documentation in perspective of equal and hashcode contract, developers should override both methods in order to achieve a fully working equality mechanism — it's not enough to just implement the equals() method.

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#equalsandhashcode #equalsandhashcodecontract #java

[jiniamitra]

Main point is equals method will get called when for key hashcode value is same.

[ragakaplish]

most easy and we explained video very very thanks a lot most helpful video cleared my all doubts keep up the good work .

[yoshitamahajan]

Thanks this is best explanation over the net..

[vinieas]

Surely Aasaam Your explanation and all the topics all very cleared mam

[DKRamnani]

What is the point of multiplying 31 with 1 and then adding it to the int value of id? You can simply add 31 to the id and return. 31 X 1 is 31 only right.

[sudarshankalvankar]

Thanks for supporting us .Video is really useful to understand the concept.

[rajajodhani]

You are really awesome in explaining things, i seen some other videos of you as well for other topics, really fell in love with your videos Thankyou

[soumyaranjan]

your explanation is very clear.Please make a video on internals of hashmap

[satishhawalppagol]

I have some few questions on equals and hashcode _ Advance-Thanks :) _ -
Suppose I have Student and Address class. Address class is field in Student(has a relationship).
If I create two objects of class Student(deep copy - Address is also created)

Is hashcode() return same / equals() return true-

1.What If I don't override equals() and hashcode() in any of class whether the two object are equal.
2.What If I override equals() and Not hashcode() in Student and nothing overridden in Address.
3.What If I only override hashcode() in Student and nothing overridden in Address.
4.What If I override equals() and Not hashcode() in Address and nothing overridden in Student.
5.What If I only override hashcode() in Address and nothing overridden in Student.
6.what if I return always true from equals() and no hashcode overridden in student and nothing overridden in Address

7.what if I return always same value from hashcode() and no equals overridden in student and nothing overridden in Address

8.what if I return always true from equals() and no hashcode overridden in Address and nothing overridden in Student

9.what if I return always same value from hashcode() and no equals overridden in Address and nothing overridden in Student.

[rahuldebnath]

I have a question on hashcode, as you are saying in this video that "hash code is a integer value which defines at which memory location does this particular object is going to store in HashTable" . As we know objects are stored in Heap memory, so does that mean heap memory is constructed using HashTable to store/manage objects ?

[menaceasif]

Thanks for ur explanation ma'am.... Really helped me to understand it better...

[naveenkumarmaddala]

Hi, Thanks for sharing the video. In your example can you explain hashcode scenario. Like equals can you take one example on hashcode and explain it. Thanks Naveen.

[ShinAkuma]

New drinking game: Take a shot every time she says "nothing but the".
JK, nice tutorials.

[srijanbiswas]

shouldnt we add @Override annotation for overridng hashcode() ??

[saritachoudhury]

your video contents are really great and helpful. But just a suggestion can you please minimize the usage of "NOTHING BUT" while explaining.

[aditis]

I can't tell you enough how awesome you are for making these videos. Thank you

[reeltorealworld]

Mam u made d variable private in employee class..plz tell me how we will acess or sort dis value in another class...

[mohitg]

thanks for the video.. you're doing a great job. all the very best & keep it up.

[dystopianNinja]

When you typecasted the object that was passed into Employee type, did you assume that if the id is same the employee name will be same too? since you called it equal only based on the id

[AmitKumar-pwln]

Thanks a lot !! This cleared my doubts