java@v1

Hygiene checks for Java projects (Maven + Gradle). Adopt it with:

extends:
  - alint://bundled/java@v1

Gated with when: facts.has_java (true if any Java build manifest exists anywhere in the tree) plus a per-rule scope_filter: { has_ancestor: [pom.xml, build.gradle, build.gradle.kts] } on per-file content rules so they only apply to files inside a Java module — useful in polyglot monorepos where Java modules sit alongside Rust / Node / Python subdirectories.

Build outputs (target/ for Maven, build/ for Gradle) are checked with git_tracked_only: true so a developer's locally-built artefacts don't trigger the rule — only committed contents do, and those are what the rule checks.

What it checks

10 rules. Each links to its section below, which explains the check and shows its definition.

Rule	Reports
java-manifest-exists `error`	Java project: `pom.xml` (Maven) or `build.gradle` / `build.gradle.kts` (Gradle) at the root is required.
java-build-wrapper-committed `info`	A committed build wrapper (`mvnw` for Maven, `gradlew` for Gradle) lets contributors and CI build the project without pre-installing the right Maven / Gradle version.
java-no-tracked-target `error`	Maven's `target/` is a build directory and shouldn't be committed.
java-no-tracked-build `error`	Gradle's `build/` is a build directory and shouldn't be committed.
java-no-class-files `error`	Compiled `.class` files don't belong in version control.
java-sources-pascal-case `warning`	Java filenames should match the public class name (PascalCase).
java-sources-final-newline `info`	File must end with a single \n.
java-sources-no-trailing-whitespace `info`	No line may end with space or tab.
java-sources-no-bidi `error`	Trojan Source (CVE-2021-42574): bidi override chars in Java sources are rejected.
java-sources-no-zero-width `error`	Zero-width characters in Java sources are rejected (review hazard).

All 10 rules run only when facts.has_java holds, so the ruleset stays quiet in repositories it doesn't apply to.

Rules

`java-manifest-exists`

Maven (pom.xml) or Gradle (Groovy or Kotlin DSL). Either is fine; mixed setups are unusual but valid.

kind: file_exists
level: error
when: facts.has_java
policy: https://maven.apache.org/guides/introduction/introduction-to-the-pom.html

Java project: pom.xml (Maven) or build.gradle / build.gradle.kts (Gradle) at the root is required.

- id: java-manifest-exists
  when: facts.has_java
  kind: file_exists
  paths:
    - pom.xml
    - build.gradle
    - build.gradle.kts
  root_only: true
  level: error
  message: >-
    Java project: `pom.xml` (Maven) or `build.gradle` /
    `build.gradle.kts` (Gradle) at the root is required.
  policy_url: "https://maven.apache.org/guides/introduction/introduction-to-the-pom.html"

`java-build-wrapper-committed`

mvnw (Maven Wrapper) or gradlew (Gradle Wrapper) make CI builds and contributor onboarding deterministic. Either script suffices.

kind: file_exists
level: info
when: facts.has_java
policy: https://docs.gradle.org/current/userguide/gradle_wrapper.html

A committed build wrapper (mvnw for Maven, gradlew for Gradle) lets contributors and CI build the project without pre-installing the right Maven / Gradle version.

- id: java-build-wrapper-committed
  when: facts.has_java
  kind: file_exists
  paths:
    - mvnw
    - gradlew
  root_only: true
  level: info
  message: >-
    A committed build wrapper (`mvnw` for Maven, `gradlew` for
    Gradle) lets contributors and CI build the project without
    pre-installing the right Maven / Gradle version.
  policy_url: "https://docs.gradle.org/current/userguide/gradle_wrapper.html"

`java-no-tracked-target`

git_tracked_only: true makes the rule fire only if target/ is *committed* — a developer's locally-built target/ (gitignored, no tracked content) is silently OK. Same shape for Gradle's build/.

kind: dir_absent
level: error
when: facts.has_java

Maven's target/ is a build directory and shouldn't be committed. Add target/ to your .gitignore.

- id: java-no-tracked-target
  when: facts.has_java
  kind: dir_absent
  paths: "**/target"
  git_tracked_only: true
  level: error
  message: >-
    Maven's `target/` is a build directory and shouldn't be
    committed. Add `target/` to your `.gitignore`.

`java-no-tracked-build`

kind: dir_absent
level: error
when: facts.has_java

Gradle's build/ is a build directory and shouldn't be committed. Add build/ to your .gitignore.

- id: java-no-tracked-build
  when: facts.has_java
  kind: dir_absent
  paths: "**/build"
  git_tracked_only: true
  level: error
  message: >-
    Gradle's `build/` is a build directory and shouldn't be
    committed. Add `build/` to your `.gitignore`.

`java-no-class-files`

kind: file_absent
level: error
when: facts.has_java

Compiled .class files don't belong in version control. Build them from the .java sources instead.

- id: java-no-class-files
  when: facts.has_java
  kind: file_absent
  paths: "**/*.class"
  git_tracked_only: true
  level: error
  message: >-
    Compiled `.class` files don't belong in version control.
    Build them from the `.java` sources instead.

`java-sources-pascal-case`

Java's class-file convention: every public top-level type lives in a file named after it, in PascalCase. Some repositories ship package-info.java / module-info.java (lowercase, snake-shaped) — those are the only standard exceptions, so they're excluded.

kind: filename_case
level: warning
when: facts.has_java

Java filenames should match the public class name (PascalCase).

- id: java-sources-pascal-case
  when: facts.has_java
  kind: filename_case
  paths:
    include: ["**/*.java"]
    exclude:
      - "**/package-info.java"
      - "**/module-info.java"
  case: pascal
  level: warning
  message: "Java filenames should match the public class name (PascalCase)."

`java-sources-final-newline`

kind: final_newline
level: info
when: facts.has_java
fix: file_append_final_newline (applied by alint fix)

- id: java-sources-final-newline
  when: facts.has_java
  kind: final_newline
  paths: "**/*.java"
  scope_filter:
    has_ancestor: [pom.xml, build.gradle, build.gradle.kts]
  level: info
  fix:
    file_append_final_newline: {}

`java-sources-no-trailing-whitespace`

kind: no_trailing_whitespace
level: info
when: facts.has_java
fix: file_trim_trailing_whitespace (applied by alint fix)

- id: java-sources-no-trailing-whitespace
  when: facts.has_java
  kind: no_trailing_whitespace
  paths: "**/*.java"
  scope_filter:
    has_ancestor: [pom.xml, build.gradle, build.gradle.kts]
  level: info
  fix:
    file_trim_trailing_whitespace: {}

`java-sources-no-bidi`

kind: no_bidi_controls
level: error
when: facts.has_java
policy: https://trojansource.codes/

Trojan Source (CVE-2021-42574): bidi override chars in Java sources are rejected.

- id: java-sources-no-bidi
  when: facts.has_java
  kind: no_bidi_controls
  paths: "**/*.java"
  scope_filter:
    has_ancestor: [pom.xml, build.gradle, build.gradle.kts]
  level: error
  message: "Trojan Source (CVE-2021-42574): bidi override chars in Java sources are rejected."
  policy_url: "https://trojansource.codes/"

`java-sources-no-zero-width`

kind: no_zero_width_chars
level: error
when: facts.has_java

Zero-width characters in Java sources are rejected (review hazard).

- id: java-sources-no-zero-width
  when: facts.has_java
  kind: no_zero_width_chars
  paths: "**/*.java"
  scope_filter:
    has_ancestor: [pom.xml, build.gradle, build.gradle.kts]
  level: error
  message: "Zero-width characters in Java sources are rejected (review hazard)."

Facts

The when: clauses above read these facts. Each is resolved once per run; alint facts prints what they resolved to in your repository.

facts:
  - id: has_java
    any_file_exists:
      - pom.xml
      - "**/pom.xml"
      - build.gradle
      - "**/build.gradle"
      - build.gradle.kts
      - "**/build.gradle.kts"
      - settings.gradle
      - "**/settings.gradle"
      - settings.gradle.kts
      - "**/settings.gradle.kts"

Customize

Every rule here can be overridden by id from your own .alint.yml: change its level, or set level: off to drop it. An id that doesn't exist is an error at config load, so a typo can't silently pass.

extends:
  - alint://bundled/java@v1
rules:
  - id: java-manifest-exists
    level: off
  - id: java-build-wrapper-committed
    level: error

To take only part of the ruleset, filter it where you extend it with only: or except::

extends:
  - url: alint://bundled/java@v1
    except: [java-manifest-exists]

Bundled rulesets covers versioning and how rulesets combine.

Source

The full ruleset definition, comments included, is committed at crates/alint-dsl/rulesets/v1/java.yml in the alint repo.