If you’re new to programming but want a career in tech, I HIGHLY RECOMMEND applying to one of Springboard’s online coding bootcamps (use code ALEXLEE for $1,000 off): bit.ly/3HX970h
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
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.
It’s not complicated to use but the implementation of a hash map is a bit more complex than just a 2d array. Hashmaps use a hash function to store the key value pair so that it doesn’t have to go through the whole hashmap using a for loop, Big O(n), when looking for a key. The hash function lookup makes it so that it is Big O(1). In other words the hash function makes it so that the lookup of a key is faster.
I don't know if you'll see this since it's an older video but you're probably the only programming tutorial RUclipsr 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.
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.
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.
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.
Dude, thank you so much for this video! I'm 2 years into a computer science degree program and this is the first explanation of a hash map that has made sense to me!
If you are 2 years into a computer science degree and you do not understand the basics of search time algorithms or hashing then either cut your losses and leave or find another service provider
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..
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!
It was originally used in cryptology as method of assigning a key that is generated using a underlying algorithm and thus this key is then used to place the value into a data structure that can be retrieved. From this it was used because the second and most commonly used reason now is to reduce the search time complexity from O(n), O(n^2) and so on; to O(1). The hash value is the return value of the function that used to generate that hash value and is used as the index positioning of the element and hence used as a key
This was extremely helpful in helping me understand hashmaps. I wasn't understanding them in lectures but this definitely helped clear things up. Thanks!!!
thanks a lot i solved the follow program only bcoz of ur help.....FIRST ONE is the one with warning and error code as following......Note: HelloWorld.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details..........SECOND ONE is correct one... FIRST CODE WITH WARNING import java.util.*; public class HelloWorld { public static void main(String[] args) { HashMap map = new HashMap();/"line with warning"/ map.put("Father", "Rob"); map.put("Mother", "Kirsten"); System.out.println(map.toString()); } } SECOND CODE WITHOUT WARNING(thanks to you) import java.util.*; public class HelloWorld { public static void main(String[] args) { HashMap map = new HashMap();/"this time no warning"/ map.put("Father", "Rob"); map.put("Mother", "Kirsten"); System.out.println(map.toString()); } }
Alex you connect really well with your audience. Also about such subjects, I always used to think that i wont understand.. But after watching my first video, the perception has been changed. Please continue making contents. All the best to you. :)
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!
Just like any other concepts, we learn basic of Java and integrate those knowledges to better understand more complex concepts. HashMap is named as it is because it possesses properties of Map and uses hashing logic in organizing and structuring data. Data Structure ✌🏼 Cool vid
If you’re new to programming but want a career in tech, I HIGHLY RECOMMEND applying to one of Springboard’s online coding bootcamps (use code ALEXLEE for $1,000 off): bit.ly/3HX970h
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
:D
Thank you for this!
This is actually the best description of HashMaps I have seen yet
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.
It’s not complicated to use but the implementation of a hash map is a bit more complex than just a 2d array. Hashmaps use a hash function to store the key value pair so that it doesn’t have to go through the whole hashmap using a for loop, Big O(n), when looking for a key. The hash function lookup makes it so that it is Big O(1). In other words the hash function makes it so that the lookup of a key is faster.
This video is awesome. Your english is clear and understandable. I like it 👍
Here, after concentrating to get what was said in the Indian accent, one time too often.
@@7own878 it gets tiring to heat the same accent from computer science tutorials all the time
I know...we can actually understand this man, unlike all the other idiots who make tutorials
I don't know if you'll see this since it's an older video but you're probably the only programming tutorial RUclipsr 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.
He understands what not knowing something was like. I really appreciate that!
For anyone with a python background, hashmaps are the same as dictionaries.
Thank you bigman
Yes
Thank you
Ah the more you know.
Saved me 11 minutes !
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.
Best hashmapping tutorial! super easy to understand well delivered! more tutorials to come THANKS! :D
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.
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.
I wonder how many people, beside me, who graduated IT thanks to you and John. I appreciate you.
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.
for anyone that is wondering, it is called a HashMap because it uses a technique called hashing.
So glad to see how your channel has grown over time. You really deserve it!
I loved the names haha "happy" and "fun", thank you so much for your explanation you made easier to understand
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.
Thank you very much Alex! I was struggling with HashMap for all day, and your video really helped!!
Bro say it’s confusing to him but now I just learn the concept in most simple way. Thank you bro 😂
I finally understood, thanks for the video!! Btw the sound of your keyboard is so satisfying😨
Thank you for explaining things so well. You make otherwise complicated things sound so easy to understand. Bless you brother!
This young dude is my favorite tutor in youtube !!
You are great my son. May God Bless you.I am 48 but steel I am your student. Thank you very much.
Couldnt imagine a better tutorial out there!
Great Video man!
Most useful on teaching me hashmaps, Thank you so much!
just as simple as u.thanks.it is a one kind of social work.we need people like u.
Dude, thank you so much for this video! I'm 2 years into a computer science degree program and this is the first explanation of a hash map that has made sense to me!
If you are 2 years into a computer science degree and you do not understand the basics of search time algorithms or hashing then either cut your losses and leave or find another service provider
@@richardpaynton8766 I appreciate the advice, but I only have 1 term left now until I graduate. But yes, my teacher was terrible.
the most simplified yet extremely informative tut on hashmap. great work m8 :)
You make everything so simple. Thanks a lot !
The UI you created it beautiful!
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!
Your Videos are straight to the point , My Coding phobia isn't anymore because of your videos...
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..
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!
Its called HashMap because it's a data structure that uses the hash function to generate a mapping of keys and their corresponding values.
Been studying for my Software Engineering Interview, and these videos are so helpful!
Thank you for the video. This covers almost everything for novice learners.
It was originally used in cryptology as method of assigning a key that is generated using a underlying algorithm and thus this key is then used to place the value into a data structure that can be retrieved. From this it was used because the second and most commonly used reason now is to reduce the search time complexity from O(n), O(n^2) and so on; to O(1). The hash value is the return value of the function that used to generate that hash value and is used as the index positioning of the element and hence used as a key
lovely dialogue delivering, excellent quality of video, concepts told in lay man terms. enjoyed and learnt. keep up the good work Alex. :)
Your videos are amazing! Thank you!!! You break down complex things so that I can better understand what's actually going on
thank you for making coding tutorials that arent mind numbing
Bro why does RUclips keep recommending this. Fine! I’m here. I clicked it
I finally understand HashMaps. Thank you so much!
Really good tutorial dude. Finally someone who dont have a crappy mic and a indian accent :D
pd : the editing was amazing too!
This was extremely helpful in helping me understand hashmaps. I wasn't understanding them in lectures but this definitely helped clear things up. Thanks!!!
I definitely recommend Alex's video! Easy to understand and follow!
These tutorials are awesome. You make java look so easy. Thanks for these easy tutorials!!
You do a great job! Simple and clear! Thank you.
thanks a lot i solved the follow program only bcoz of ur help.....FIRST ONE is the one with warning and error code as following......Note: HelloWorld.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details..........SECOND ONE is correct one...
FIRST CODE WITH WARNING
import java.util.*;
public class HelloWorld {
public static void main(String[] args) {
HashMap map = new HashMap();/"line with warning"/
map.put("Father", "Rob");
map.put("Mother", "Kirsten");
System.out.println(map.toString());
}
}
SECOND CODE WITHOUT WARNING(thanks to you)
import java.util.*;
public class HelloWorld {
public static void main(String[] args) {
HashMap map = new HashMap();/"this time no warning"/
map.put("Father", "Rob");
map.put("Mother", "Kirsten");
System.out.println(map.toString());
}
}
Thank you so much, you're an awesome teacher.
As usual GREAT! Understanding the concept in 11 minutes :)
you don't give weird analogies like other youtube videos good work
love the teachers who make understanding fun. thank you sir
Damn, his Java tutorials are totally understandable, thanks
Thanks for taking time to create content that helps me understand Java! Great job!
Legend
great tutorial. I understand it alot than my teacher. Thanyou! post more java tutorial
Wow thank you I was unable to understand hash maps until I stumbled upon your video. Thank you :)
i don't usually write comments but your tutorials are so good and helpful.
keep going !
You simplified it perfectly.. thank you sir
that's just straight as an arrow. Awesome bro.
What type of keyboard is that? The sound is so satisfying XD
looks like a HHKB TypeS (torpre silent 45g switches)
Excellent video, I understood everything. Thank you!
Thank you Alex!! it's always fun and helpful watching your videos :) keep it up!
instead of typing system.out.println()
use sout followed by ctrl+space or cmd+space
or just do sysout followed by ctrl + space.
Extremly good explained!
Way better then my proffesor! Sure its not advanced, but i at least undertood the basicis of HashMap.
Thank you.
Alex you connect really well with your audience. Also about such subjects, I always used to think that i wont understand.. But after watching my first video, the perception has been changed. Please continue making contents. All the best to you. :)
You sound gay do you want to get on your knees for him
Helped out at lot! Very concise!
Thank you for these easy-to-understand tutorials, subscribed now!!
Hey Alex you're amazing I really love the way you teach...Stay happy 😉
UNDERSTANDABLE !!! Very good video ! Your explanation is clear and simple ! Good job ! I like it.
pls make a full session on java , your style is best .
Gosh I wish I could watch ur vid earlier! I just love the way you teach, clear and understandable. PLZ UPLOAD MORE! LUV YA ♥
you're a great teacher, keep going 💪
Teaching method really awesome. Wish your good health.
Your videos are very easy to follow !
You're awesome dude! Very nice and concise explanations!
Best hashmap tutorial ever!
My favorite java tutor. if I am not mistaking if u want order you can use TreeMap
This was really helpful. Thank you so much!
Thank you for making this. It was extremely helpful!
your explanations are the best! thank you so much!
really ur explaination was good, after watching video i got clear idea about hash map thank you.
So simple explanation. Thanks!
You're the best coding tutor!
Thanks a bunch for the tutorials man, appreciate it
You definitely helped me out! Thanks
Wow!
You made it easy for me!
Thank you so much! ❤️❤️
That was great! Many thanks, bro!
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!
This Channel is underrated
Really like your videos, thanks for putting them up!
Quick question though.... why do you not use your Mac keyboard :) ?
This was most helpful. I also want one of your keyboards but for now I'm gonna stay with my measly CTRL from drop.
That keyboard giving me the tingles XD
Very nice man! Helped me a lot👍🏼
Can u show a demo of string , vector hashmap ?
Thank you so much!! Finally a good explanation! Can you please make more videos on Data Structures :-)
Just like any other concepts, we learn basic of Java and integrate those knowledges to better understand more complex concepts. HashMap is named as it is because it possesses properties of Map and uses hashing logic in organizing and structuring data. Data Structure ✌🏼
Cool vid