Add Android and Java library examples.

KeepAnnotationsSample/README.md

@@ -4,19 +4,57 @@ This examples shows the use of the `androidx.annotation.keep` Gradle plugin.
 
 - This programmatically generates `keep` rules when an `app` / `android library` / `java library` module uses `androidx.annotation:annotation-keep`.
 
-
 ## Testing
 
-```kotlin
+### Android apps and Library Modules
 
-// For app modules
+```bash
+
+// App Modules
 
 ./gradlew <variantName>ExtractKeepRules
 
-// For android library modules
+// For Android Library Modules
 
 ./gradlew <variantName>KeepRulesTransformAar
+```
 
+### Java / Kotlin Library Modules
+
+For Java Libraries, you need to do the following. 
+
+* Apply the Gradle Plugin.
+
+```kotlin
+plugins {
+    alias(libs.plugins.androidx.annotation.keep)
+}
 ```
 
-The generated keep rules end up in `build/generated/variantName/androidx.annotation.keep.rules.pro`.
+* Register a new task that can generate the artifact with keep rules.
+
+```kotlin
+val outputJar = project.tasks.named<org.gradle.jvm.tasks.Jar>("jar").flatMap { task ->
+    task.archiveFile
+}
+
+val outputFile = outputJar.map { file -> "keep${file.asFile.name.uppercaseFirstChar()}" }
+
+// Register the JAR transform for extracting keep rules.
+val artifactTask = annotationKeep.registerJavaArchiveTransform(
+    taskName = "keepRulesJar",
+    input = outputJar,
+    fileName = outputFile
+)
+```
+
+* Register the output artifact for publication.
+
+```kotlin
+// Register the new artifact.
+project.configurations.configureEach {
+    if (name == "apiElements" || name == "runtimeElements") {
+        outgoing.artifact(artifactTask)
+    }
+}
+```

KeepAnnotationsSample/build.gradle.kts

@@ -2,4 +2,6 @@ plugins {
     alias(libs.plugins.android.application) apply false
     alias(libs.plugins.kotlin.compose) apply false
     alias(libs.plugins.androidx.annotation.keep) apply false
+    alias(libs.plugins.android.library) apply false
+    alias(libs.plugins.jetbrains.kotlin.jvm) apply false
 }

KeepAnnotationsSample/gradle/libs.versions.toml

@@ -9,6 +9,9 @@ lifecycleRuntimeKtx = "2.11.0"
 activityCompose = "1.13.0"
 kotlin = "2.4.20"
 composeBom = "2026.08.00"
+appcompat = "1.6.1"
+material = "1.10.0"
+jetbrainsKotlinJvm = "2.4.20"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -26,8 +29,12 @@ androidx-compose-ui-tooling-preview = { group = "androidx.compose.ui", name = "u
 androidx-compose-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
 androidx-compose-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
 androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" }
+androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "appcompat" }
+material = { group = "com.google.android.material", name = "material", version.ref = "material" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }
 kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 androidx-annotation-keep = { id = "androidx.annotation.keep", version.ref = "annotationKeep" }
+android-library = { id = "com.android.library", version.ref = "agp" }
+jetbrains-kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "jetbrainsKotlinJvm" }

KeepAnnotationsSample/java-library/.gitignore

@@ -0,0 +1 @@
+/build

KeepAnnotationsSample/java-library/build.gradle.kts

@@ -0,0 +1,42 @@
+import org.gradle.kotlin.dsl.support.uppercaseFirstChar
+
+plugins {
+    id("java-library")
+    alias(libs.plugins.jetbrains.kotlin.jvm)
+    alias(libs.plugins.androidx.annotation.keep)
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
+val outputJar = project.tasks.named<org.gradle.jvm.tasks.Jar>("jar").flatMap { task ->
+    task.archiveFile
+}
+
+val outputFile = outputJar.map { file -> "keep${file.asFile.name.uppercaseFirstChar()}" }
+
+// Register the JAR transform for extracting keep rules.
+val artifactTask = annotationKeep.registerJavaArchiveTransform(
+    taskName = "keepRulesJar",
+    input = outputJar,
+    fileName = outputFile
+)
+
+// Register the new artifact.
+project.configurations.configureEach {
+    if (name == "apiElements" || name == "runtimeElements") {
+        outgoing.artifact(artifactTask)
+    }
+}
+
+dependencies {
+    implementation(libs.androidx.annotation.keep)
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_11
+    }
+}

KeepAnnotationsSample/java-library/src/main/java/org/example/java/library/PlainLocator.kt

@@ -0,0 +1,16 @@
+package org.example.java.library
+
+import androidx.annotation.keep.UsesReflectionToConstruct
+
+interface PlainLocator {
+    companion object {
+        @UsesReflectionToConstruct(classConstant = PlainLocatorImpl::class)
+        fun load(): PlainLocator {
+            val klass = Class.forName(PlainLocatorImpl::class.java.name)
+            @Suppress("DEPRECATION")
+            return klass.newInstance() as PlainLocator
+        }
+    }
+}
+
+private class PlainLocatorImpl : PlainLocator

KeepAnnotationsSample/library/.gitignore

@@ -0,0 +1 @@
+/build

KeepAnnotationsSample/library/build.gradle.kts

@@ -0,0 +1,29 @@
+plugins {
+    alias(libs.plugins.android.library)
+    alias(libs.plugins.androidx.annotation.keep)
+}
+
+android {
+    namespace = "org.example.library"
+    compileSdk {
+        version = release(37)
+    }
+    defaultConfig {
+        minSdk = 24
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+}
+
+dependencies {
+    implementation(libs.androidx.annotation.keep)
+    implementation(libs.androidx.appcompat)
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.material)
+    testImplementation(libs.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
+    androidTestImplementation(libs.androidx.junit)
+}

KeepAnnotationsSample/library/src/androidTest/java/org/example/library/ExampleInstrumentedTest.kt

@@ -0,0 +1,24 @@
+package org.example.library
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("org.example.library.test", appContext.packageName)
+    }
+}

KeepAnnotationsSample/library/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>

KeepAnnotationsSample/library/src/main/java/org/example/library/LibraryResourceLocator.kt

@@ -0,0 +1,16 @@
+package org.example.library
+
+import androidx.annotation.keep.UsesReflectionToConstruct
+
+interface LibraryResourceLocator {
+    companion object {
+        @UsesReflectionToConstruct(classConstant = LibraryResourceLocatorImpl::class)
+        fun load(): LibraryResourceLocator {
+            val klass = Class.forName(LibraryResourceLocatorImpl::class.java.name)
+            @Suppress("DEPRECATION")
+            return klass.newInstance() as LibraryResourceLocator
+        }
+    }
+}
+
+private class LibraryResourceLocatorImpl : LibraryResourceLocator

KeepAnnotationsSample/library/src/main/keepRules/rules.keep

@@ -0,0 +1,12 @@
+# Add project specific R8 rules here.
+# AGP will combine all keep rule files in src/main/keepRules to pass to R8
+#
+# For more details, see
+#   https://d.android.com/r/tools/r8/keep-rules
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}

KeepAnnotationsSample/library/src/test/java/org/example/library/ExampleUnitTest.kt

@@ -0,0 +1,17 @@
+package org.example.library
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}

KeepAnnotationsSample/settings.gradle.kts

@@ -10,7 +10,7 @@ pluginManagement {
         mavenCentral()
         gradlePluginPortal()
         maven {
-            url = uri("https://androidx.dev/snapshots/builds/16303799/artifacts/repository")
+            url = uri("https://androidx.dev/snapshots/builds/16312043/artifacts/repository")
         }
     }
 }
@@ -23,7 +23,7 @@ dependencyResolutionManagement {
         google()
         mavenCentral()
         maven {
-            url = uri("https://androidx.dev/snapshots/builds/16303799/artifacts/repository")
+            url = uri("https://androidx.dev/snapshots/builds/16312043/artifacts/repository")
             content {
                 includeGroupByRegex("androidx\\.annotation.*")
             }
@@ -34,3 +34,5 @@ dependencyResolutionManagement {
 
 rootProject.name = "Example"
 include(":app")
+include(":library")
+include(":java-library")