RFR: 8329760: Add indexOf(Predicate<? super E> filter) to java..util.List interface [v6]

[Evemose]

> **Subject**
> Addition of Predicate-based `indexOf` and `lastIndexOf` methods to `java.util.List`
> 
> **Motivation**
> The motivation behind this proposal is to enhance the functionality of the `List` interface by providing a more flexible way to find the index of an element. Currently, the `indexOf` and `lastIndexOf` methods only accept an object as a parameter. This limits the flexibility of these methods as they can only find the index of exact object matches.
> 
> The proposed methods would accept a `Predicate` as a parameter, allowing users to define a condition that the desired element must meet. This would provide a more flexible and powerful way to find the index of an element in a list.
> 
> Here is a brief overview of the changes made in this pull request:
> 
> 1. Added the `indexOf(Predicate<? super E> filter)` method to the `List` interface.
> 2. Added the `lastIndexOf(Predicate<? super E> filter)` method to the `List` interface.
> 3. Implemented these methods in all non-abstract classes that implement the `List` interface.
> 
> The changes have been thoroughly tested to ensure they work as expected and do not introduce any regressions. The test cases cover a variety of scenarios to ensure the robustness of the implementation.
> 
> For example, consider the following test case:
> 
> List<String> list = new ArrayList<>();
> list.add("Object one");
> list.add("NotObject two");
> list.add("NotObject three");
> 
> int index1 = list.indexOf(s -> s.contains("ct t"));
> System.out.println(index1); // Expected output: 1
> int index2 = list.lastIndexOf(s -> s.startsWith("NotObject"));
> System.out.println(index2); // Expected output: 2
> 
> 
> Currently, to achieve the same result, we would have to use a more verbose approach:
> 
> int index1 = IntStream.range(0, list.size())
>                      .filter(i -> list.get(i).contains("ct t"))
>                      .findFirst()
>                      .orElse(-1);
> System.out.println(index1); // Output: 1
> int index2 = IntStream.range(0, list.size())
>                          .filter(i -> list.get(i).startsWith("NotObject"))
>                          .reduce((first, second) -> second)
>                          .orElse(-1);
> System.out.println(index2); // Output: 2
> 
> 
> I believe these additions would greatly enhance the functionality and flexibility of the `List` interface, making it more powerful and user-friendly. I look forward to your feedback and am open to making any necessary changes based on your suggestions.
> 
> Thank you for considering this proposal.
> 
> Best regards
> 
> PS: In ...

Evemose has updated the pull request incrementally with 14 additional commits since the last revision:

 - Update LinkedList.java
 - Update LinkedList.java
 - Reformat LinkedList.java
 - Removed trailing whitespace in Collections.java
 - Update CopyOnWriteArrayList.java
 - Reformated imports in Vector.java
 - Reformated imports in CopyOnWriteArrayList.java
 - Removed on-demand import from SpliteratorTraversingAndSplittingTest.java
 - Update ListFactories.java
 - Update ReverseOrderListView.java
 - ... and 4 more: https://git.openjdk.org/jdk/compare/5beec920...d7f5e97e

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18639/files
  - new: https://git.openjdk.org/jdk/pull/18639/files/5beec920..d7f5e97e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18639&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18639&range=04-05

  Stats: 59 lines in 7 files changed: 33 ins; 6 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/18639.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18639/head:pull/18639

PR: https://git.openjdk.org/jdk/pull/18639