👷 Add Spotless Java linting to CI pipeline

Add automated Java code style checking using Spotless with:
- Google Java Format (AOSP style) for Android-friendly formatting
- New ci/java-lint/ Gradle project for linting
- New 'spotless' job in GitHub Actions workflow
- Excludes third-party code (org/kamranzafar/jtar/)

Downstream CI jobs now depend on both flake8 and spotless checks.

Author: AndreMiras

.github/workflows/push.yml

@@ -30,9 +30,26 @@ jobs:
         pip install tox>=2.0
         tox -e pep8
 
+  spotless:
+    name: Java Spotless check
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout python-for-android
+      uses: actions/checkout@v5
+    - name: Set up Java 17
+      uses: actions/setup-java@v4
+      with:
+        distribution: 'temurin'
+        java-version: '17'
+    - name: Set up Gradle
+      uses: gradle/actions/setup-gradle@v4
+    - name: Run Spotless check
+      working-directory: ci/java-lint
+      run: gradle spotlessCheck
+
   test:
     name: Pytest [Python ${{ matrix.python-version }} | ${{ matrix.os }}]
-    needs: flake8
+    needs: [flake8, spotless]
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
@@ -61,7 +78,7 @@ jobs:
 
   ubuntu_build:
     name: Build test APP [ ${{ matrix.runs_on }} | ${{ matrix.bootstrap.name }} ]
-    needs: [flake8]
+    needs: [flake8, spotless]
     runs-on: ${{ matrix.runs_on }}
     strategy:
       matrix:
@@ -119,7 +136,7 @@ jobs:
 
   macos_build:
     name: Build test APP [ ${{ matrix.runs_on }} | ${{ matrix.bootstrap.name }} ]
-    needs: [flake8]
+    needs: [flake8, spotless]
     runs-on: ${{ matrix.runs_on }}
     strategy:
       matrix:
@@ -193,7 +210,7 @@ jobs:
 
   ubuntu_rebuild_updated_recipes:
     name: Test updated recipes for arch ${{ matrix.android_arch }} [ ubuntu-latest ]
-    needs: [flake8]
+    needs: [flake8, spotless]
     runs-on: ubuntu-latest
     # continue on error to see failures across all architectures
     continue-on-error: true
@@ -225,7 +242,7 @@ jobs:
 
   macos_rebuild_updated_recipes:
     name: Test updated recipes for arch ${{ matrix.android_arch }} [ ${{ matrix.runs_on }} ]
-    needs: [flake8]
+    needs: [flake8, spotless]
     runs-on: ${{ matrix.runs_on }}
     # continue on error to see failures across all architectures
     continue-on-error: true

ci/java-lint/build.gradle

@@ -0,0 +1,60 @@
+// Java Lint Configuration for python-for-android
+// This file configures Spotless to lint Java source files across all bootstraps
+
+plugins {
+    id 'java'
+    id 'com.diffplug.spotless' version '6.25.0'
+}
+
+// Repositories for plugin dependencies (e.g., google-java-format)
+repositories {
+    mavenCentral()
+}
+
+// Define the root directory for bootstrap Java sources
+def bootstrapsDir = "${rootProject.projectDir}/../../pythonforandroid/bootstraps"
+
+// Collect all Java source directories from all bootstraps
+def javaSourceDirs = []
+file(bootstrapsDir).eachDir { bootstrapDir ->
+    def srcDir = new File(bootstrapDir, 'build/src/main/java')
+    if (srcDir.exists()) {
+        javaSourceDirs.add(srcDir.absolutePath)
+    }
+}
+
+sourceSets {
+    main {
+        java {
+            srcDirs = javaSourceDirs
+        }
+    }
+}
+
+spotless {
+    java {
+        // Target all Java files from the source directories
+        target fileTree(bootstrapsDir) {
+            include '**/build/src/main/java/**/*.java'
+            // Exclude third-party vendored code
+            exclude '**/org/kamranzafar/jtar/**'
+        }
+
+        // Use Google Java Format with AOSP style (Android-friendly, slightly relaxed)
+        googleJavaFormat('1.19.2').aosp()
+
+        // Remove unused imports
+        removeUnusedImports()
+
+        // Trim trailing whitespace
+        trimTrailingWhitespace()
+
+        // Ensure files end with a newline
+        endWithNewline()
+    }
+}
+
+// Disable compilation - we only want to lint, not build
+tasks.withType(JavaCompile).configureEach {
+    enabled = false
+}

ci/java-lint/gradle.properties

@@ -0,0 +1,9 @@
+# Gradle properties for Java lint project
+# Disable daemon for CI environments
+org.gradle.daemon=false
+
+# Use parallel execution where possible
+org.gradle.parallel=true
+
+# Configure JVM memory
+org.gradle.jvmargs=-Xmx512m

ci/java-lint/settings.gradle

@@ -0,0 +1,3 @@
+// Java Lint Project Settings
+// This project is used for linting Java source files in CI
+rootProject.name = 'p4a-java-lint'