To try to loop back on my original point... The "underlying problem" that I think should be addressed by some new internal class (or suite of classes) is the "array builder" problem. This is where you're doing "append, append, append, ..., use read-only thereafter".
Currently people use ArrayList for that, or for primitive arrays, homebrew it with System.arraycopy() - or maybe I'm missing something like this that already exists? I would like to see JDK standard "array builders" for primitive types and reference types that use fixed sized (power-of-two) segments internally. These can be internal classes for now. Then the faster ByteArrayOutputStream becomes just a wrapper around "ByteArrayBuilder" or whatever we call it. This is all just my opinion, I'm curious if others perceive the same gap that I do? -Archie On Fri, Apr 11, 2025 at 10:15 AM Archie Cobbs <archie.co...@gmail.com> wrote: > On Fri, Apr 11, 2025 at 8:11 AM Engebretson, John <jeng...@amazon.com> > wrote: > >> It seems like a good general-purpose list but I wouldn’t recommend it as >> a direct replacement for either ArrayList or LinkedList; in the former case >> the risk is slower random accesses, and in the latter the risk is to head >> modifications. >> > > Interesting results. However I don't think comparing this to both > ArrayList and LinkedList is really fair. Developers choose an > implementation based on how they know they are going to use it: If they are > just adding stuff, they choose ArrayList. If they know they need to > insert/remove in the middle, they choose LinkedList. If they need to > add/remove from both ends, they choose ArrayDeque. Etc. > > So the optimal design changes depending on which "flavor" of list usage > the developer is implying when they choose some implementation class. > > E.g., if you wanted to target the "ArrayList flavor', then you'd use fixed > size, power-of-two segments. Then get() remains constant time, and insert > and remove remain as painfully slow as ever, but the common "list builder" > usage pattern of "append, append, append, ..., use read-only thereafter" > gets a lot faster. > > OTOH variable-sized chunks makes lots of sense for the "LinkedList" > flavor. In fact you could have a LinkedList<T> that just uses an > ArrayList<ArrayDeque<T>> internally :) > > -Archie > > -- > Archie L. Cobbs > -- Archie L. Cobbs
