LinkedList vs ArrayList in Java Tutorial - Which Should You Use?

Updated answer: Although the complexity analysis in this video still stands, in real world applications, ArrayList is the better choice for virtually every single use case. See the pinned comment below for more info.

LinkedLists are a great data structure to be familiar with, but they can be confusing. If you're familiar with ArrayLists in Java and how to use them, then LinkedLists can be used in the same way.

But when should you use a LinkedList vs. an ArrayList? How do you use them - are there any differences. We'll go over all of that and more in this beginner/intermediate Java video tutorial lesson.

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[prototype]

I've been working with Java for nearly 15 years now. I remember studying linked list in and various other data structures in college. John, you explained something that college professors flunked folks over so much better and in a matter of minutes rather than days. Bravo sir.

[findlestick]

Your channel is the only one that has increased my enthusiasm for Java, tenfold. Your videos really are a breath of fresh air here on YouTube. I’m going to watch all your vids and thumb-them-up in gratitude. 👍

[goerekt]

I once had a job to improve performance of a java application. Best improvement was done by just exchange a LinkedList to an ArrayList, because it was used to read a lot by index. Very simple change, but massive impact.

[jam-yhil]

I don't know how your videos can be so condensed but still thorough. Thanks from all of the Computer Science majors.

[Lyosha.]

The arrayList does not leave a "space" for the new element in the new array. It instead duplicates all the values from the index into which you want to move the new element into . Those duplicates are positioned one index down from that point (you get one doubled item ) and then that doubled item is replaced with the new one you are moving so the process it's actually longer than what you explained :)

[gabenixon]

July 14, 2022 - Properly learned ArrayList and LinkedList. Thanks John!

[wickedsnuk]

It was like those lectures where the instructor teaches so smoothly so s/he puts everything in your mind without you noticing.

[alexanderrizzi]

This is *by far* the easiest video to help understand this concept. As a relatively new programmer, I always found it somewhat puzzling to have different implementations of the List interface, but this video clears so many things up and gives actual reasons for their existence! Cheers!

[dedz]

If someone is wondering why arrays have a constant time to get an element, it's because to get an element from the array, it makes a calculation, a really simple calculation actually.. the programs already knows the position that the array is located in the memory, and already knows the type of data the array is holding, so it can calculate the location of any index with a constant number of steps by doing : memoryPosition + (index * typeSize).

So, knowing the “start” position of the array, you just need to multiply the index by the amount of memory that this specific type takes. Let’s say you have an array that holds 100 int numbers, and let’s say the array is located at the space 1000 of the memory.. and int numbers take 4 bytes of memory each. So, to get the 50th element, we just need to multiply the index by the size of bytes (49 * 4) and we will get 196 bytes, now, just add the 1000 (the position that the array starts in the memory), you will get 1196 bytes, this is where the index number 49 is located. That's why it's constant, because you can have a 3 size array or a size array, the array will always do the same math calculation to get the index that you want to get.

[lootster]

I have problems understanding LinkedList despite reading numerous articles online. Your video is a god's gift!

[jvsnyc]

ArrayList is still great if you are adding tons of stuff only to the end. It only needs to move stuff over when adding *not* at the end, otherwise it just places the element at the end and updates the current size. Additionally, it only needs to create a new array and copy everything over when the reserved capacity is exhausted. If you are keeping a reference to some node deep in the midst of the LinkedList, and adding or removing around *that*, then the LinkedList is faster. Also, if for some reason you are often adding and removing right at the beginning, a LinkedList comes into its own. Lastly, there is more memory overhead and less cache coherence with LinkedList. A funny quote I remember:
“Does anyone actually use LinkedList? I wrote it, and I never use it.” Joshua Bloch
Searching that gives some interesting information on it. As you said tho, for small data sizes, either of them would work great, you will likely never notice a difference unless your data gets larger.

[ryuujisancodes]

As someone who hasn't touched java except when an interview required it - watching your videos made me feel like I can code anything in java now. You're an excellent teach, bro. You've got a gift for sure.

[SpooxyCowboy]

It’s so refreshing to hear an explanation that doesn’t have a heavy accent. Almost all my professors are hard to understand and it makes it difficult to learn

[amirulidzham]

I learn java since 2014 but now I understand it. Huge thanks

[ginandi]

In most use cases, amortized analysis shows equivalence of run time.
Linked lists, however, lead to more cache misses (array can be bulk copied to cache with much fewer misses) which puts array in a huge advantage for practical reasons as well.

[slaki]

Amazingly clear video, great job. Just a minor remark: To emphasize that the interface of the two lists is the same you could have used just List<String> as their type. Generally, that is the recommended way anyway.

[DassVeryGood]

Crazy how someone can explain all this clearly and simply in 10 minutes. Where my uni would take 2 mins of explaining nothing with a minimalistic slide showing what a linked list looks like. Thank you so much

[ayushgupta]

Wish i had someone to teach me these stuff earlier…I had to learn these things the hard way. Awesome video man!!
Just one thing I think array list uses a load factor of (0.75) to decide when to scale up not when the list is totally full(e.g. like reached 10)

[bekbolots]

How can a man be so precise with his teaching! Great job.

[flytoinfinityvivi]

This is the most amazing course ever! Exactly what I want to know regarding of why use one from the other. Best examples and I got it rightaway. This guy is genius and should be a professor instead.