(#) Using Discouraged Private API !!! WARNING: Using Discouraged Private API This is a warning. Id : `DiscouragedPrivateApi` Summary : Using Discouraged Private API Severity : Warning Category : Correctness Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 3.5.0 (August 2019) Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor See : https://developer.android.com/preview/restrictions-non-sdk-interfaces Implementation : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/PrivateApiDetector.kt) Tests : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/PrivateApiDetectorTest.kt) Usage of restricted non-SDK interface may throw an exception at runtime. Accessing non-SDK methods or fields through reflection has a high likelihood to break your app between versions, and is being restricted to facilitate future app compatibility. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test/pkg/application/ReflectionTestJava.java:11:Warning: Reflective access to addAssetPath, which is not part of the public SDK and therefore likely to change in future Android releases [DiscouragedPrivateApi] Method m1 = AssetManager.class.getDeclaredMethod("addAssetPath", String.class); ------------------------------------------------------------------ src/test/pkg/application/ReflectionTestJava.java:12:Warning: Reflective access to addAssetPath, which is not part of the public SDK and therefore likely to change in future Android releases [DiscouragedPrivateApi] Method m2 = assetManager.getClass().getDeclaredMethod("addAssetPath", String.class); ----------------------------------------------------------------------- src/test/pkg/application/ReflectionTestJava.java:13:Warning: Reflective access to addAssetPath, which is not part of the public SDK and therefore likely to change in future Android releases [DiscouragedPrivateApi] Method m3 = AssetManager.class.getDeclaredMethod("addAssetPath", path.getClass()); --------------------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here are the relevant source files: `src/test/pkg/application/ReflectionTestJava.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package test.pkg.application; import android.content.res.AssetManager; import java.lang.reflect.Method; public class ReflectionTestJava { private static void addAssetPath(AssetManager assetManager) throws Exception { String path = "foo/bar"; Method m1 = AssetManager.class.getDeclaredMethod("addAssetPath", String.class); Method m2 = assetManager.getClass().getDeclaredMethod("addAssetPath", String.class); Method m3 = AssetManager.class.getDeclaredMethod("addAssetPath", path.getClass()); Method m4 = AssetManager.class.getDeclaredMethod("invalidateCachesLocked", int.class); Method m5 = AssetManager.class.getDeclaredMethod("invalidateCachesLocked", Integer.TYPE); Method m6 = AssetManager.class.getDeclaredMethod("invalidateCachesLocked", Integer.class); // OK, doesn't exist Class activityClass = Class.forName("android.app.Activity"); Class bundleClass = Class.forName("android.os.Bundle"); Method m7 = activityClass.getDeclaredMethod("dispatchActivityPostCreated", bundleClass); } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ `src/test/pkg/application/ReflectionTestKotlin.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers package test.pkg.application; import android.content.res.AssetManager class ReflectionTestKotlin { private fun addAssetPath(assetManager: AssetManager) { val path = "foo/bar" val m1 = AssetManager::class.java.getDeclaredMethod("addAssetPath", String::class.java) val m2 = assetManager.javaClass.getDeclaredMethod("invalidateCachesLocked", Int::class.javaPrimitiveType) val m3 = assetManager.javaClass.getDeclaredMethod("invalidateCachesLocked", Int::class.java) // OK, doesn't exist val m4 = AssetManager::class.java.getDeclaredMethod("addAssetPath", path.javaClass) val activityClass = Class.forName("android.app.Activity") val bundleClass = Class.forName("android.os.Bundle") val m5 = activityClass.getDeclaredMethod("dispatchActivityPostCreated", bundleClass) } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/PrivateApiDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `PrivateApiDetector.testJavaReflection`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=192708. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("DiscouragedPrivateApi") fun method() { forName(...) } ``` or ```java // Java @SuppressWarnings("DiscouragedPrivateApi") void method() { forName(...); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection DiscouragedPrivateApi problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="DiscouragedPrivateApi" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'DiscouragedPrivateApi' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore DiscouragedPrivateApi ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).