HashMap Java Tutorial #50 

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Exemplary tutorial, as always. Timings + my notes below that might help others: 1:45 An example of how hashmaps can help 2:05 Creating and naming a hashmap 2:40 How to add values to a hashmap using the .put method 3:52 Why you should use a generic and data type for type safety when creating a hashmap + how to add this 4:25 Why you need 'Integer' [i.e. class type] for a hashmap (can't take primitive 'int' type) 5:00 Test print of hashmap (default output displays in set notation) 5:30 Calling a specific value from the hashmap - .get call 5:50 Start of more advanced hashmap functions - user + password example 6:15 Creating a hashmap with specific type for type safety 6:33 How to add users and passwords - .put method 7:32 How to remove elements from a hash map - .remove method 8:08 Check if hashmap contains a specific value - .containsValue 8:42 Difference between Values and Keys in a hashmap using .containsValue and .containsKey method calls 9:23 How to replace a value (password) - .replace method 10:10 Key difference between hashmaps and array lists - hashmaps don't have a specific order whereas array lists have an index 11:00 Simple summary of what a hashmap is

This video is awesome. Your english is clear and understandable. I like it 👍

Yes the name itself used to make me think that this HashMap thing is one of the most complicated things in Java. Your tutorial made it look like a piece of cake. :) Thanks! keep up the good work.

This is actually the best description of HashMaps I have seen yet

I don't know if you'll see this since it's an older video but you're probably the only programming tutorial RU-vidr that's relatable. The rest of them are super smart and do know what they're talking about (so are you obviously) but for some reason, you admitting that a certain topic or part of a topic confuses you helps me understand the material more when you explain it.

2:00 It's called HashMap because it uses hash key to access values in the background and implements Map interface and extends AbstractMap class. If you would write your custom HashMap it would be array of linked lists. Length of the array would not be equal to number of stored key-value pairs. Instead array stores linked list heads, where each list node has hash key, value and points to next node. Hash key is hash version of the key you inserted. To access the value nodes are iterated until hash key matches.

For anyone with a python background, hashmaps are the same as dictionaries.

i have watched too many java channels but i found you is the best the best thing about is you is you start to explain a topic in such a way that nothing more required to learn that perticular topic. please bother upload all the java tutorials like spring mvc swings etc.

Love your tutorials, so clear and concise! you just get to the point and it just makes sense!

This is so helpful. Your explanations and presentation are perfect.

Best hashmapping tutorial! super easy to understand well delivered! more tutorials to come THANKS! :D

Been studying for my Software Engineering Interview, and these videos are so helpful!

Thank you for explaining things so well. You make otherwise complicated things sound so easy to understand. Bless you brother!

So glad to see how your channel has grown over time. You really deserve it!

Thank you very much Alex! I was struggling with HashMap for all day, and your video really helped!!

Seriously you taught a semestre worth of studies under 20 min. I thank you. I couldn't figure this out until your video. Please make more videos on data structures. I get your explanations.

I was working on a master order assignment where we had to make a map of cookie variety and its numBoxes sold. This video was very helpful since he basically said, here is the assignment. You're gonna need to know Maps. I appreciate the tutorials. Thank you so much.

That keyboard is amazing! Thanks for clearing up hashmaps for me, makes it easier when we get there at school.

now that's amazing how something so abstract to me has become instantly crystal clear. you are awesome!

for anyone that is wondering, it is called a HashMap because it uses a technique called hashing.

Couldnt imagine a better tutorial out there! Great Video man!

In a technical aptitude exams hashing question were asked ..had no idea what hashing was and didn't do well but now it is crisp and clear thanks to u Sir..

The UI you created it beautiful!

Your videos are amazing! Thank you!!! You break down complex things so that I can better understand what's actually going on

This was extremely helpful in helping me understand hashmaps. I wasn't understanding them in lectures but this definitely helped clear things up. Thanks!!!

the most simplified yet extremely informative tut on hashmap. great work m8 :)

I finally understood, thanks for the video!! Btw the sound of your keyboard is so satisfying😨

just as simple as u.thanks.it is a one kind of social work.we need people like u.

Thank you for the video. This covers almost everything for novice learners.

These tutorials are awesome. You make java look so easy. Thanks for these easy tutorials!!

Most useful on teaching me hashmaps, Thank you so much!

You make everything so simple. Thanks a lot !

I wonder how many people, beside me, who graduated IT thanks to you and John. I appreciate you.

I loved the names haha "happy" and "fun", thank you so much for your explanation you made easier to understand

I finally understand HashMaps. Thank you so much!

As usual GREAT! Understanding the concept in 11 minutes :)

Thanks for taking time to create content that helps me understand Java! Great job!

Thank you for these easy-to-understand tutorials, subscribed now!!

You simplified it perfectly.. thank you sir

You do a great job! Simple and clear! Thank you.

love the teachers who make understanding fun. thank you sir

Wow thank you I was unable to understand hash maps until I stumbled upon your video. Thank you :)

Hello Alex and thank you very much for your videos. They are awesome! For this video in particular, it was not clear to me what are the differences of HashMap and ArrayList, and how too choose which to use. Thank you again!

I definitely recommend Alex's video! Easy to understand and follow!

lovely dialogue delivering, excellent quality of video, concepts told in lay man terms. enjoyed and learnt. keep up the good work Alex. :)

You are great my son. May God Bless you.I am 48 but steel I am your student. Thank you very much.

your explanations are the best! thank you so much!

Your videos are very easy to follow !

You definitely helped me out! Thanks

This was really helpful. Thank you so much!

You're awesome dude! Very nice and concise explanations!

Thank you! this was so clear

Excellent video, I understood everything. Thank you!

So simple explanation. Thanks!

Teaching method really awesome. Wish your good health.

Helped out at lot! Very concise!

Thank you for making this. It was extremely helpful!

That was great! Many thanks, bro!

you explained it effortless

Such a good tutorial, straightforward and useful

Very nice man! Helped me a lot👍🏼

Bro say it’s confusing to him but now I just learn the concept in most simple way. Thank you bro 😂

UNDERSTANDABLE !!! Very good video ! Your explanation is clear and simple ! Good job ! I like it.

Wow! You made it easy for me! Thank you so much! ❤️❤️

great tutorial. I understand it alot than my teacher. Thanyou! post more java tutorial

You are the best 🙂 simple and clear without complications 👏👏

This helped me a lot, thank you Alex!

Thanks a bunch for the tutorials man, appreciate it

really ur explaination was good, after watching video i got clear idea about hash map thank you.

Thank you so much, you're an awesome teacher.

you don't give weird analogies like other youtube videos good work

This was most helpful. I also want one of your keyboards but for now I'm gonna stay with my measly CTRL from drop.

Thanks dude! Really good !!

you're a great teacher, keep going 💪

Thank you so much - I've been struggling with this for almost a week unable to get my code to work

Wow ...such an amazing explanation

Thank Alex, very clear explanation of HashMap.

Legend

that's just straight as an arrow. Awesome bro.

Great Tutorial 😀 Thanks a lot !

Thanks man, you made it super easy

Thank you so much!! Finally a good explanation! Can you please make more videos on Data Structures :-)

This young dude is my favorite tutor in youtube !!

Thank you Alex!! it's always fun and helpful watching your videos :) keep it up!

pls make a full session on java , your style is best .

Very clear explanation 👍 thanks 😀

Gosh I wish I could watch ur vid earlier! I just love the way you teach, clear and understandable. PLZ UPLOAD MORE! LUV YA ♥

Really easy to understand, best tutorial! :)

Ivbeen stressing out over this for days cuz of my final. Learned it conpletely under 12 min just now. Just need some practice and the final is gonna be ez. thanks bud!

Best hashmap tutorial ever!

Your tutorials are awesome :D

Your Videos are straight to the point , My Coding phobia isn't anymore because of your videos...

My favorite java tutor. if I am not mistaking if u want order you can use TreeMap

Simply and great, thanks

Hey Alex you're amazing I really love the way you teach...Stay happy 😉

Beautifully explained.😄

Great tutorial Alex.

Thx , nice explanation btw keep up the good work 👍

You're the best coding tutor!