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Rename _ identifier to __ for Java ≤ 8 source files#1063

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timtebeek merged 8 commits intomainfrom
Jenson3210/moscow-to-must-have
Apr 16, 2026
Merged

Rename _ identifier to __ for Java ≤ 8 source files#1063
timtebeek merged 8 commits intomainfrom
Jenson3210/moscow-to-must-have

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@Jenson3210 Jenson3210 commented Apr 16, 2026 •
edited by moderne-meeseeks Bot
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Summary

  • Add RenameUnderscoreIdentifier recipe that renames single-underscore identifiers (_) to double-underscore (__) in Java source files with source compatibility ≤ Java 8

  • Handles all identifier positions: local variables, method parameters, fields, method names (declaration + call sites), member references, and class names

  • Gated by UsesJavaVersion(1, 8) precondition — no changes on Java 9+

  • Registered in Java8toJava11 composite recipe

  • Closes https://github.com/moderneinc/customer-requests/issues/2221

Test plan

  • Local variable rename with reference sites
  • Method parameter rename with usage in body
  • Instance field rename with this. access
  • Method name rename (declaration + invocation)
  • Catch parameter, lambda parameter, for-each loop variable
  • No change on Java 9+ source files
  • No change for _foo, foo_, my_value identifiers
  • No change for __ (idempotent)

@Jenson3210
Rename _ identifier to __ for Java ≤ 8 source files
a6a2a62 
In Java 9+, `_` became a reserved keyword causing compile errors.
This recipe renames single-underscore identifiers to double-underscore
as a prerequisite migration step for projects upgrading from Java 8.

Closes moderneinc/customer-requests#2221
@github-project-automation github-project-automation Bot moved this to In Progress in OpenRewrite Apr 16, 2026
timtebeek
timtebeek reviewed Apr 16, 2026
View reviewed changes
Comment thread src/test/java/org/openrewrite/java/migrate/lang/RenameUnderscoreIdentifierTest.java Outdated
@Jenson3210
Extract package-private RenameIdentifierVisitor for reuse in tests
9e358aa 
Addresses review feedback: the visitor logic is now shared between the
recipe and the test setup recipe via RenameIdentifierVisitor(oldName, newName).
@Jenson3210
Move RenameIdentifierVisitor to static nested class
bb7eee4 
Inline the visitor as a static nested class of RenameUnderscoreIdentifier
instead of a separate top-level file.
@Jenson3210
Regenerate recipes.csv
51612f5
@Jenson3210
Use @requiredargsconstructor on RenameIdentifierVisitor
b4f2a68
@Jenson3210
Use import for @requiredargsconstructor
da6a933
@Jenson3210
Use @value on RenameIdentifierVisitor
ebd2400
@Jenson3210
Remove redundant private final modifiers on @value fields
de1588f
@github-project-automation github-project-automation Bot moved this from In Progress to Ready to Review in OpenRewrite Apr 16, 2026
@timtebeek timtebeek merged commit 461609f into main Apr 16, 2026
1 check passed
@timtebeek timtebeek deleted the Jenson3210/moscow-to-must-have branch April 16, 2026 09:56
@github-project-automation github-project-automation Bot moved this from Ready to Review to Done in OpenRewrite Apr 16, 2026
mergify Bot added a commit to robfrank/linklift that referenced this pull request May 3, 2026
@mergify
chore(deps): bump org.openrewrite.recipe:rewrite-migrate-java from 3.…
0573d36 
…30.1 to 3.34.0 [skip ci]

Bumps [org.openrewrite.recipe:rewrite-migrate-java](https://github.com/openrewrite/rewrite-migrate-java) from 3.30.1 to 3.34.0.
Release notes

*Sourced from [org.openrewrite.recipe:rewrite-migrate-java's releases](https://github.com/openrewrite/rewrite-migrate-java/releases).*

> 3.34.0
> ------
>
> What's Changed
> --------------
>
> * Ensure `case` always has a space before the label in `IfElseIfConstructToSwitch` by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1071](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1071)
> * Add `UsePredicateNot` to replace cast-and-negate with `Predicate.not(..)` by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1072](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1072)
>
> **Full Changelog**: <openrewrite/rewrite-migrate-java@v3.33.0...v3.34.0>
>
> 3.33.1
> ------
>
> **Full Changelog**: <openrewrite/rewrite-migrate-java@v3.33.0...v3.33.1>
>
> 3.33.0
> ------
>
> What's Changed
> --------------
>
> * Add URLEqualsHashCodeRecipes to Java best practices by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1058](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1058)
> * Add --add-opens JVM args to surefire/failsafe for Java 25 by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1055](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1055)
> * Collapse UpgradeDockerImageVersion cartesian via ChangeFrom capture by [`@​jkschneider`](https://github.com/jkschneider) in [openrewrite/rewrite-migrate-java#1060](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1060)
> * Add NoJodaTime to Java best practices by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1061](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1061)
> * Support `copyOf` migration for Guava by [`@​greg-at-moderne`](https://github.com/greg-at-moderne) in [openrewrite/rewrite-migrate-java#1062](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1062)
> * Rename `_` identifier to `__` for Java ≤ 8 source files by [`@​Jenson3210`](https://github.com/Jenson3210) in [openrewrite/rewrite-migrate-java#1063](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1063)
> * Fix `ClassCastException` on parenthesized initializers in `var` recipes by [`@​knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-migrate-java#1064](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1064)
> * Gate Kotlin-based Java version cap on actual Kotlin sources by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1066](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1066)
> * Fix `MigrateCollections*` template errors on complex expression contexts by [`@​knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-migrate-java#1067](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1067)
>
> **Full Changelog**: <openrewrite/rewrite-migrate-java@v3.32.1...v3.33.0>
>
> v3.32.1
> -------
>
> What's Changed
> --------------
>
> * Remove parentheses from single unnamed lambda parameters by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1054](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1054)
> * Skip Kotlin and Groovy files in ReplaceUnusedVariablesWithUnderscore by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1056](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1056)
>
> **Full Changelog**: <openrewrite/rewrite-migrate-java@v3.32.0...v3.32.1>
>
> 3.32.0
> ------
>
> What's Changed
> --------------
>
> * Cap Java version at 24 for Kotlin <2.3 in UpgradeToJava25 by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1035](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1035)
> * Inline JavaTemplate fields at their usage sites by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1036](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1036)
> * Use `JavaTemplate.apply()` static method by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1037](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1037)
> * Fix ClassCastException in UseVarForGenericMethodInvocations by [`@​knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-migrate-java#1039](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1039)
> * Upgrade Mockito to 5.17.x in Java 25 migration recipe by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1041](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1041)
> * Migrate Mojarra and Glassfish JSF dependencies to Jakarta Faces by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1040](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1040)
> * Upgrade jakarta.annotation-api to 3.0.x in Jakarta EE 11 recipe by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1042](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1042)
> * Move type-use annotations to array brackets during JSpecify migration by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1038](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1038)
> * Add explicit casts for visitor visit() return type by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1049](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1049)
> * Add UseVarForTypeCast and UseVarForConstructors to UseVar recipe by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1050](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1050)
> * Replace Collections.emptyXXX with Immutable Static Factory Methods by [`@​mkarg`](https://github.com/mkarg) in [openrewrite/rewrite-migrate-java#1045](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1045)
> * Fix `AddMissingMethodImplementation` generating stubs for inherited methods by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1051](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1051)
> * Add EnableLombokAnnotationProcessor to LombokBestPractices by [`@​timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#1052](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/1052)

... (truncated)


Commits

* [`61c1777`](openrewrite/rewrite-migrate-java@61c1777) Extract documentation examples from tests
* [`95028a5`](openrewrite/rewrite-migrate-java@95028a5) Add `UsePredicateNot` to replace cast-and-negate with `Predicate.not(..)` ([#1](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1)...
* [`a58b8b2`](openrewrite/rewrite-migrate-java@a58b8b2) Ensure `case` always has a space before the label in `IfElseIfConstructToSwit...
* [`eac4344`](openrewrite/rewrite-migrate-java@eac4344) Fix `MigrateCollections*` template errors on complex expression contexts ([#1067](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1067))
* [`0ca5cc8`](openrewrite/rewrite-migrate-java@0ca5cc8) Extract documentation examples from tests
* [`968a22f`](openrewrite/rewrite-migrate-java@968a22f) Gate Kotlin-based Java version cap on actual Kotlin sources ([#1066](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1066))
* [`a471dd1`](openrewrite/rewrite-migrate-java@a471dd1) [Auto] SDKMAN! Java candidates as of 2026-04-20T1116
* [`3b7b950`](openrewrite/rewrite-migrate-java@3b7b950) Fix `ClassCastException` on parenthesized initializers in `var` recipes ([#1064](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1064))
* [`461609f`](openrewrite/rewrite-migrate-java@461609f) Rename `_` identifier to `__` for Java ≤ 8 source files ([#1063](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1063))
* [`634e7d9`](openrewrite/rewrite-migrate-java@634e7d9) Support `copyOf` migration for Guava ([#1062](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/1062))
* Additional commits viewable in [compare view](openrewrite/rewrite-migrate-java@v3.30.1...v3.34.0)
  
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@timtebeek timtebeek timtebeek approved these changes

@steve-aom-elliott steve-aom-elliott Awaiting requested review from steve-aom-elliott

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