openrewrite / openrewrite/rewrite-static-analysis

replace `Collection` removal using loops with `removeIf` to avoid `ConcurrentModificationException`

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recipe
Dominant language
Java
Stars
62
Forks
112
Avg merge
1d 19h
Merged PRs (30d)
40

Description


    List<Integer> integers = new ArrayList<>();
        integers.add(1);
        integers.add(2);
        integers.add(3);
        integers.add(4);

        for (Integer integer : integers) {
            if (integer  == 2) {
                integers.remove(integer);
            }
        }

Exception in thread "main" java.util.ConcurrentModificationException
	at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1043)
	at java.base/java.util.ArrayList$Itr.next(ArrayList.java:997)
	at Scratch.main(scratch_5.java:12)

A common solution to the problem above is to use iterators :


Iterator<Integer> iter = integers.iterator();

 while (iter.hasNext()) {
            Integer i = iter.next();

            if (i == 2){
                iter.remove();
            }

        }

But using removeIf is more compact and cleaner. It also avoid ConcurrentModificationException


 integers.removeIf(integer -> integer == 2);


Streams is another option, but doing so will return a new list and that is likely not desirable in this case

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No source file or test is named. Start by locating the Java static-analysis recipe that handles collection-removal loops, then compare its existing behavior with the examples in this issue. Done means the matching loop is replaced with removeIf while preserving in-place removal and avoiding ConcurrentModificationException.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
tooling
Issue type
Refactor
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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