Android SDK version properties

Android applications can set a number of SDK version properties in their build.gradle file. The Android build.gradle documentation explains what those properties mean for the application in general. This document explains how those properties affect NDK builds.

compileSdkVersion

This property has no effect on NDK builds. API availability for the NDK is instead governed by minSdkVersion. This is because C++ symbols are eagerly resolved at library load time rather than lazily resolved when first called (as they are in Java). Using any symbols that are not available in the minSdkVersion will cause the library to fail to load on OS versions that do not have the newer API, regardless of whether or not those APIs will be called.

targetSdkVersion

Similar to Java, the targetSdkVersion of your app can change the runtime behavior of native code. Behavior changes in the system are, when feasible, only applied to apps with a targetSdkVersion greater than or equal to the OS version that introduced the change.

While application developers generally know their app's targetSdkVersion, this API is useful for library developers that cannot know which targetSdkVersion their users will choose.

At runtime, you can get the targetSdkVersion used by an application by calling android_get_application_target_sdk_version(). This API is available in API level 24 and later. This function has the following signature:

/**
 * Returns the `targetSdkVersion` of the caller, or `__ANDROID_API_FUTURE__` if
 * there is no known target SDK version (for code not running in the context of
 * an app).
 *
 * The returned values correspond to the named constants in `<android/api-level.h>`,
 * and is equivalent to the AndroidManifest.xml `targetSdkVersion`.
 *
 * See also android_get_device_api_level().
 *
 * Available since API level 24.
 */
int android_get_application_target_sdk_version() __INTRODUCED_IN(24);

Other behavior changes might depend on the device API level. You can get the API level of the device your application is running on by calling android_get_device_api_level(). This function has the following signature:

/**
 * Returns the API level of the device we're actually running on, or -1 on failure.
 * The returned values correspond to the named constants in `<android/api-level.h>`,
 * and is equivalent to the Java `Build.VERSION.SDK_INT` API.
 *
 * See also android_get_application_target_sdk_version().
 */
int android_get_device_api_level();

maxSdkVersion

This property has no effect on NDK builds.

minSdkVersion

The minSdkVersion set in your build.gradle file determines which APIs are available at build time (see compileSdkVersion to understand why this differs from Java builds), and determines the minimum version of the OS that your code will be compatible with.

The minSdkVersion of your application is made available to the preprocessor via the __ANDROID_API__ macro. This macro is defined automatically by Clang, so no header needs to be included to use it. For NDK builds, this macro is always defined.

The minSdkVersion is used by the NDK to determine what features may be used when compiling your code. For example, this property determines which FORTIFY features are used in libc, and may also enable performance or size improvements (such as GNU hashes or RELR) for your binaries that are not compatible with older versions of Android. Even if you do not use any new APIs, this property still governs the minimum supported OS version of your code. Despite this, it is possible that libraries will load on an older version of the OS. Do not rely on, as it may differ across NDK versions, OS versions, or individual devices.