RFR: 8143850: Add indexed get() and set() methods to ArrayDeque

[Rémi Forax]

On Mon, 12 May 2025 18:24:27 GMT, Archie Cobbs <acobbs at openjdk.org> wrote:

> Because it is backed by an array, the `ArrayDeque` class has the ability to get and replace any element in the list (accessed by index) in constant time. However, this capability is not exposed in the API.
> 
> Please review this PR which adds the following two new methods to `ArrayDeque`:
> * `public E get(int index)`
> * `public E set(int index, E element)`

src/java.base/share/classes/java/util/ArrayDeque.java line 384:

> 382:     public E set(int index, E element) {
> 383:         if (element == null)
> 384:             throw new NullPointerException();

please add curly braces around `throw ...` as described in the style guide.

src/java.base/share/classes/java/util/ArrayDeque.java line 388:

> 386:     }
> 387: 
> 388:     private E getset(int index, E newValue) {

Please keep the implementation simple and avoid this kind of tricks, we are not sure in the future if E will be forever nullable so calling getset(index, null) may not be valid in the future.

test/jdk/java/util/ArrayDeque/IndexedAccess.java line 38:

> 36: 
> 37: public class IndexedAccess {
> 38: 

I think some tests are missing, if the ArrayDeque is empty, if the ArrayDeque is full, at least

test/jdk/java/util/ArrayDeque/IndexedAccess.java line 75:

> 73: 
> 74:         try {
> 75:             a.set(0, null);

assertThrow ?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25189#discussion_r2087336980
PR Review Comment: https://git.openjdk.org/jdk/pull/25189#discussion_r2087335755
PR Review Comment: https://git.openjdk.org/jdk/pull/25189#discussion_r2087338994
PR Review Comment: https://git.openjdk.org/jdk/pull/25189#discussion_r2087337713