#12 - Difference b/w ConcurrentHashMap & SynchronizedMap in Java || (HashTable vs HashMap)

In this video, I have explained what is the different between ConcurrentHashMap & SynchronizedMap.
We will also see why HashTable is not preferred for Multi Threading - concurrent environment.
Difference between HashMap vs HashTable vs ConcurrentHashMap vs SynchronizedMap in Java.
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[@sureshgarine]

I would say one word --- "AWESOME". I remember my days of engineering - studied about Operating Systems - process synchronization. Thank you for the lucid explanation.

[@jatinsharma3792]

I wish that I would have studied Computer Science it’s attractive branch, I am enjoying learning now.

[@harithasri8372]

Naveen totally addicted to your videos. Ur videos are simply awesome for complete beginners. Many channels explain about put and add method or about null values and null keys. But if u take a concept u will be true to urself and with us and explain everything about it. Thank you so much.

[@pablo-escobar-here]

if providing detailed explanation is an art that you are the Picasso of it Naveen!! Thank You very much😊

[@viveksrivastava4264]

Aisa koi engineering college me padha deta to maazzaa aa jata.....
You are really really amazing ... Itne simple words me koi bhi nai bata sakta.... :)

[@gopalpandurangan9768]

Thanks, Naveen for your wonderful demonstration on this Topic.

[@Fortheluvoffood]

Really enjoying these series... used to run away from this topic while prepping but you have made it really very easy to understand.. thanks a ton

[@nobleman2704]

best explained ever
tbh. I would suggest to explain it by saying bucket instead of segment

[@Vithal_Nivargi]

first time I entered your channel I felt awesome content!
Thank you so much for your effort

[@naveenautomationlabs]

Welcome to Naveen automation labs

[@simm5622]

Thank you so much, you made it super easy to understand. 🏆🏆🏆🏆🏆

[@sakshiaggarwal6199]

Super amazing. Thanks a lot for this premium content.

[@dharanyuvi6951]

Really a great thanks Naveen bro.., Information like these are gem 🥰

[@RahulKumar-xu4ft]

Thank u so much from the bottom of my heart.....such a way u hv explained Amazing keep on...

[@naveenautomationlabs]

Glad that you liked it 🙂

[@MrAsgar123]

Awesome Explain. Thank you so much

[@2anshumansehgal]

Thanks Naveen for this video..super important

[@jackcoolguy123]

Awesome explanation.
Just one correction. HashMap was there before JDK 1.5 too.
I had given SCJP for jdk 1.4 and HashMap was there.

[@alokprajapati4504]

I think this is the best explanation, and cleared the concept.

[@tkk1369]

wow!!!To the point :)

[@vipulrohilla1383]

Thanks for explaining this wonderfully.

[@sriram6148]

Great work! Good job!!
Note: hashmap was introduced in 1.2 itself. Pls add atleast a note in your video so that people are not misguided.

[@keplerk]

Info i didn't know i needed to know, thanks !

[@santhoshsandeep]

Thanks for the topic Naveen bro#naveen👍

[@13success66]

Very beautiful explanation thanks a lot

[@anjanaraja43]

Hi naveen.. Clear crisp 👏
I have some doubt.
If one thread writing/ updating data to segment one and
Another thread accessing data from another segment same point of time...
So there is a chance of in accuracy right..
Is there any solution

[@monumoon5515]

really ur so talented

[@nikhilninawe7648]

Thanks u saved my life

[@softwaredevnk166]

Nice explanation. Thanks!!

[@jatinsharma3792]

Beautifull...

[@Thd369]

Thank you so much.

[@WMohanty]

amazing, get well soon thanks

[@vengateshm2122]

How to prevent concurrent modification exception in arraylist?

[@nivedaravi2241]

Great explanation. Surprised. Just subscribed.

[@sarthakbrahmbhatt1092]

I think there is issue when collision occurs and if particular bucket is locked by another thread then it must wait . Otherwise next time when we find value of index or bucket address with hascode it will point to same index where it should be or value wont be able to be found. I am just asking.

[@fathimasyed4232]

clear explanation .. great !!

[@irckdwrld]

@Naveen AutomationLabs Thanks for the awesome explanation😊Just subscribed😁
Can you please explain segment level locking (till java7) vs Bucket level locking (in java8). Thanks in advance!!

[@keerthu7055]

great explanation bro:)

[@SurajYadav-yd2cu]

what if two threads try to access same segement ...... wil it not throw concurrentModiificationexception at that time .....................

[@HungNguyen-nd6tz]

Many thanks (y)

[@krishnakasam5725]

what happens when more than 16 threads are trying to write on 16 segments of the object in concurrent hashmap?

[@pratapjavasingh3239]

Few doubt why only one null key introduce in a hashmap not the multiple and this is the same functionality why not implemented hash table can u tell me answer Naveen sir and also usecases? don't say legacy reason respective of hashtable

[@svalyavasvalyava9867]

thank you so much!!!

[@parulgarg7429]

how to ensure for the other threads to read the updated value in the segment if one thread is writing at the same time in concurrent hash map.

[@irckdwrld]

I know it's late, but could be a reference for future viewers.... The "Reading" thread/s can directly read from ConcurrentHashMap. If there is/are update operation(s) happening at same segment/bucket, after all the update operations only, the read operation/thread can execute. We don't have to do anymore settings.
As from JavaDocs of SE8 version:
More formally, an update operation for a given key bears a happens-before relation with any (non-null) retrieval for that key reporting the updated value.

[@parulgarg7429]

@@irckdwrld Thanks doubt..cleared

[@zhaoqingchris]

Amazing video, however Segment lock was abandoned since Java 8, it now uses CAS + Synchronisation to guarantee thread safety

[@irckdwrld]

Can you please explain segment level locking (till java7) vs Bucket level locking (in java8). Thanks in advance!!

[@kingajable]

superb

[@DeepakVishwakarma-uv4yr]

Sir, what will be the virtual capacity once 16 indexes of nodes are filled? For e.g In ArrayList if I add more values than the default capacity i.e 10 My virtual capacity becomes 15, 22, and so on. What will be the virtual capacity of the HashMap once go beyond the default virtual capacity?

[@cinthiyavincent9527]

Each node create a balanced binary tree once the threshold value reached I guess

[@danceayush8128]

Great job 👍

[@abdularsath2715]

Amazing naveen when will you post like this for python .

[@chandansharma6849]

Sir i have a doubt please help me ......
If i deploy my application on the server and then every user will get a thread of application......
If there is any synronised map then only one user have lock on it no other user can access utill first user leave .....
Or syncronised map is safe from sub threads of main thread which every user get on server.....
Please clear my doubt sir..

[@yaswanthravuri8450]

Nice explanation

[@meenakshibhasin9456]

Hi sir, in case of concurrentHashMap if all the buckets are writing and one more thread wants to write so it will wait for one of the thread to be free ?

[@rubyyadav935]

Vedio 13,14 is not there... Directly 15 vedio (hashmap interview questions is listed)... And please make a vedio for fast-fail and fast-safe..,comparator ane comparable..

[@amritasharma5390]

Thank you 😊

[@naveenautomationlabs]

You're welcome 😊

[@Pakhichetna]

@Naveen
When I'm using below code snippet to print key and value of syncMap, I'm getting NoSuchElementException. Can you please help?
Iterator itr = syncMap.entrySet().iterator();
while(itr.hasNext()) {
System.out.println("key = "+itr.next().getKey()+" Value = "+itr.next().
getValue()); }

[@vsprasadavantsa7203]

Thanks

[@ashuiet]

What is EnumMap and How to use in real time scenarios

[@srianshworld3942]

great explanation

[@pranjal.sharma]

very helpful 👏👏👏

[@dipukumar-wd6ys]

Hi sir, I have one doubt on concurrenthashmap suppose in one segment can it allow two thread for Two operation (like read, write) ?

[@OODevelopers]

Yes it is allowed

[@chandrasekhar5858]

After loosing interview, i landed here 🙏🙏🙏🙏🙏

[@satishkoppisetty927]

segment and bucket both refer to same component ? someone please help

[@archu4cts]

Awesome

[@swapnilsam5164]

Awesome 😎

[@catmom6572]

Great work! Reminds me of my professor Dr. Subir in U of Windsor.

[@sanketnegi1]

I am looking for advantages of synchronised over concurrent..
1. It allows null values and 1 null key.
2. Consistency is weak in concurrent.
I want to understand what does this weak consistency mean

[@ImranKhan-mc6vf]

Confused a bit, so when we say ConcurrentHashMap is divided in 16 segments and a thread tries to write to it, does it mean it is writing in "Key", "Value" pair (for an instance, "Key1", "Value1").
If it is so, what happens let's say 2nd thread goes to write "Key1", "Value2" to the map simultaneously and new segment is provided for it to write? Does the map has 2 same keys now, which I believe not is the case, so what exactly is happening?

[@subhrajyotiroy1471]

I guess when another thread goes to write "Key1", "Value2", it will generate same hashcode and then navigate to same index which currently earlier thread is using and this is locked by thread 1. So when writing operation is done by thread1, thread2 will update the value there.

[@vlvn0191]

5:00

[@RaviKumar-lg7hu]

You should tell "not syncronized means".
Not "syncronized means" @ 00:28

[@rahulsoni-lx5rb]

🙌awsmmm!

[@arnavpatil583]

ConcurrentModificationException

[@ameynaik2743]

How is it taking care of this th-cam.com/video/UwurUtvil7w/w-d-xo.html ?