I try to implement `LinkedList<E>` (from Java), but what Kotlin list should I extend? `ArrayLi...

# multiplatform

[Robert]

I try to implement LinkedList<E> (from Java), but what Kotlin list should I extend? ArrayList is final, so can't use that, and just List makes me implement every method myself 😞 extending MutableList is even worse....

[Dominaezzz]

AbstractList?

[Robert]

Thank you! That's what I was looking for. Now it forces me to implement get(index: Int) (and for mutable list a few more). Where do I get/save those values? Just create another list in a property of it?

[Dominaezzz]

What values? (Also, I recommend extending AbstractCollection for a linked list).

[Robert]

The values for the list....

[Robert]

It wants me to implement get(index), what should I return....

[Dominaezzz]

Return the element at that index in the list.

[Robert]

Obviously, but how to get that, as I can't use this.get(index) as that's the method I am implement, where is the data stored?

[Dico]

You need to implement that part, you decide

[Dico]

Consider extending AbstractMutableList, it will make more sense because you'll need to implement add and stuff.

[Dico]

You should not forget to override iterator as otherwise your iterator will be extremely slow, something like O(n2/2)

[Robert]

But to save the data, I have to implement another list right? But eventually there has to be a list that saves data by itself instead of wrapping another list. Wonder how this list saves its data

[Dico]

Look at the source for java.util.LinkedList

[kpgalligan]

Not the worlds best example of an implementation but this https://github.com/touchlab/Stately/blob/master/src/commonMain/kotlin/co/touchlab/stately/collections/SharedLinkedList.kt

[kpgalligan]

You can use in native, but it’s designed to work multithreaded. Performance was not a huge concern

[coletz]

https://github.com/touchlab/Stately/blob/4b17057ad5d55f51f4ccf971cf79e51585ad2324/src/commonMain/kotlin/co/touchlab/stately/collections/SharedLinkedList.kt#L35 dat comment tho lol