setup-java-gitignore

name	setup-java-gitignore
description	Create or update the root `.gitignore` file for a Java project — compiled classes, logs, packaged

Setup Java Gitignore

Create or refresh the root .gitignore for a Java project, using this repository's own .gitignore as the concrete reference template. Never overwrite an existing .gitignore without showing the user exactly what would change and getting explicit approval first — a .gitignore can carry hand-added, project-specific entries that must not be silently dropped.

Step 1 — Check whether .gitignore already exists at the repository root

• Not found: continue to Step 2. Because there's nothing to lose, the final write in Step 5 happens without needing approval — go straight from composing the content to writing it, then report in Step 6.
• Found: read its current content now — it matters later, both to avoid proposing duplicate entries and because Step 4 must preserve any hand-written, project-specific lines this skill doesn't know how to regenerate. Warn the user up front that a .gitignore already exists and this skill will propose changes for them to review rather than overwrite it silently. Continue to Step 2.

Step 2 — The universal base template

Every Java project gets this baseline, adapted from this repository's own .gitignore (the parts of it that are not specific to Hermes):

# Compiled class file
*.class

# Log file
*.log

# BlueJ files
*.ctxt

# Mobile Tools for Java (J2ME)
.mtj.tmp/

# Package Files #
*.jar
*.war
*.nar
*.ear
*.zip
*.tar.gz
*.rar

# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
replay_pid*

This section is unconditional — include it verbatim regardless of build tool or IDE.

Step 3 — Detect project-specific additions

Don't guess; only add a section below when the thing it targets is actually present in the target repository.

• Build tool output directory:

  • pom.xml at the root → Maven project: add

    /target/
    

  • build.gradle or build.gradle.kts at the root → Gradle project: add

    /build/
    .gradle/
    

  • Both can exist in unusual multi-tool setups — include both blocks if so; if neither exists, skip this section and note it in Step 6 (there's no build tool to infer an output directory for yet).

• IntelliJ IDEA (.idea/): if a .idea/ directory exists, or there's no strong signal either way (IntelliJ is the default assumption for a Java project), use this repository's own convention: track most of .idea/ (shared code-style and inspection settings are useful to commit) but ignore the machine-specific or noisy files:

  /.idea/codeStyles/codeStyleConfig.xml
  /.idea/.gitignore
  /.idea/compiler.xml
  /.idea/copilot.data.migration.agent.xml
  /.idea/copilot.data.migration.edit.xml
  /.idea/encodings.xml
  /.idea/jarRepositories.xml
  /.idea/misc.xml
  /.idea/vcs.xml
  

  If the user says they'd rather ignore all of .idea/ outright (some teams prefer that instead of this repository's partial-tracking convention), use /.idea/ as a single line instead — ask via AskUserQuestion if it's not already clear from an existing .gitignore's current handling of .idea/.

• VS Code: if .vscode/ exists, add .vscode/ (Java projects on VS Code rarely benefit from committing workspace settings the way IntelliJ's code style does).

• Eclipse: if .classpath, .project, or .settings/ exist, add .classpath, .project, and .settings/.

• Generated build-info properties file: grep pom.xml (or build.gradle*) for a Groovy/Maven (or equivalent Gradle) build step that writes a build-info.properties-style file, mirroring how this repository's own groovy-maven-plugin execution writes src/main/resources/com/irurueta/hermes/build-info.properties — the pattern to look for is a build script step that computes version/commit/branch metadata and writes it under . If found, extract the actual output path from that script (don't hardcode Hermes's package) and add the matching line, e.g.:

Step 4 — Compose the proposed content

Concatenate Step 2's base template with whichever Step 3 sections actually matched, each under its own comment header for readability (e.g. # Maven, # IntelliJ IDEA, # Antora docs). If Step 1 found an existing .gitignore, merge rather than duplicate: keep any of its lines that aren't already covered by the composed template (hand-added project-specific ignores must survive), and don't repeat a line that's already present verbatim.

Step 5 — If .gitignore already existed, get approval before writing

Skip this step entirely if Step 1 found no existing file — proceed straight to Step 6's write.

• Show the user the proposed new .gitignore content as a diff against the current file (writing the draft to a temp path and running git diff --no-index <current> <draft> gives a clean unified diff).
• Ask via AskUserQuestion whether to: (a) accept and write the proposed content, (b) skip and leave the existing .gitignore untouched. There is no partial-apply option here — if the user wants only some of the proposed lines, let them say so in free text and revise the draft before writing.
• Only proceed to Step 6 on explicit acceptance.

Step 6 — Write .gitignore and report

Write the composed content (Step 4, incorporating any edits from Step 5's review) to .gitignore at the repository root. Then summarize: whether the file was newly created or updated, which conditional sections from Step 3 were included versus skipped and why (e.g. "no Eclipse section — no .classpath/.project found", "no build-info entry — no such generated-file step in pom.xml"), and — if .gitignore already existed — whether the user accepted or skipped the proposed changes.