What are Android Annotations and what are they used for?

Android Annotations are a set of annotations provided by the Android framework to add metadata to Java code. They are used for the following purposes:

1. Providing information to the compiler: Annotations like @Override, @Deprecated, and @SuppressWarnings give instructions to the compiler to detect errors and suppress warnings[1][3].

2. Generating code: Annotations can be used by annotation processors to generate additional code, XML files, and other artifacts during compilation[1][3].

3. Attaching metadata at runtime: Annotations like @Nullable and @NonNull can be accessed at runtime using reflection to determine if a method parameter or return value is nullable[4].

4. Enabling static code analysis: Annotations like @VisibleForTesting and @RestrictTo provide information to static code analysis tools to enforce access restrictions and identify code that should not be called from outside a specific scope[4].

5. Documenting APIs: Annotations like @CallSuper, @UiThread, and @WorkerThread document the expected behavior of methods and classes, helpin...