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What's New in Android NDK Download 21 and How to Get Started


Android NDK Download 21: How to Install and Use the Latest Version




If you are an Android developer who wants to improve the performance, security, and compatibility of your app, you might want to consider using the Android Native Development Kit (NDK). The Android NDK is a toolset that lets you implement parts of your app in native code, using languages such as C and C++. In this article, we will show you how to download and install the latest version of the Android NDK, which is 21, and how to use it in your Android app. We will also cover some common issues that you might encounter when using the Android NDK and how to fix them.




android ndk download 21



What is Android NDK and why do you need it?




The Android NDK is a set of tools that allows you to access native code libraries from your Java or Kotlin code. Native code libraries are compiled for a specific processor architecture, such as ARM or x86, and can run faster and more efficiently than Java or Kotlin code. Native code libraries can also provide features that are not available in the Android framework, such as low-level access to hardware, graphics, audio, and network.


The benefits of using native code in your Android app




Using native code in your Android app can have several advantages, such as:


  • Performance: Native code can run faster and use less memory than Java or Kotlin code, especially for computationally intensive tasks such as image processing, encryption, or machine learning.



  • Security: Native code can be harder to reverse engineer or tamper with than Java or Kotlin code, which can protect your app from hackers or pirates.



  • Compatibility: Native code can help you support older devices or devices with different architectures than the ones supported by the Android framework.



The challenges of using native code in your Android app




Using native code in your Android app can also have some drawbacks, such as:


  • Complexity: Native code can be more difficult to write, debug, and maintain than Java or Kotlin code, especially if you are not familiar with the native languages or tools.



  • Portability: Native code can be less portable than Java or Kotlin code, which means that you might have to write different versions of your native library for different architectures or platforms.



  • Stability: Native code can cause crashes or memory leaks if it is not written correctly or if it interacts poorly with the Java or Kotlin code.



How to download and install Android NDK 21




To use the Android NDK in your app, you need to download and install it on your development machine. There are two ways to do this: using Android Studio or manually.


The prerequisites for installing Android NDK 21




Before you install the Android NDK 21, you need to make sure that you have the following prerequisites:


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  • An IDE: You need an integrated development environment (IDE) that supports native development, such as , which is the official IDE for Android development.



  • A JDK : You need a Java Development Kit (JDK) that matches the minimum version required by Android Studio, which is JDK 11. You can download it from or use the one bundled with Android Studio.



  • A CMake: You need a CMake tool that can generate native build scripts for your native library project. You can download it from or use the one bundled with Android Studio.



  • An NDK: You need an Android NDK that matches the minimum version required by your app, which is NDK 21. You can download it from or use the one bundled with Android Studio.



The steps for installing Android NDK 21 using Android Studio




The easiest way to install the Android NDK 21 is to use Android Studio, which can automatically download and configure the NDK for you. Here are the steps to follow:


  • Open Android Studio and create a new project or open an existing one.



  • Go to File > Project Structure > SDK Location.



  • Under Android NDK Location, click Download.



  • Select NDK (Side by side) and choose 21.4.7075529, which is the latest stable version of NDK 21.



  • Click OK and wait for the download to finish.



  • Click Apply and OK.



Congratulations, you have successfully installed the Android NDK 21 using Android Studio!


The steps for installing Android NDK 21 manually




If you prefer to install the Android NDK 21 manually, you can follow these steps:


  • Go to and download the NDK package for your operating system.



  • Extract the NDK package to a location of your choice, such as C:\Android\ndk\21.4.7075529.



  • Add the NDK location to your system environment variables, such as ANDROID_NDK_HOME=C:\Android\ndk\21.4.7075529.



  • Add the NDK location to your project local.properties file, such as ndk.dir=C\:\\Android\\ndk\\21.4.7075529.



Congratulations, you have successfully installed the Android NDK 21 manually!


How to use Android NDK 21 in your Android app




To use the Android NDK 21 in your app, you need to create a native library project, link it to your app module, and call native methods from your Java or Kotlin code.


How to create a native library project using CMake




A native library project is a folder that contains your native source files, such as C or C++ files, and a CMakeLists.txt file that defines how to build your native library. Here are the steps to create a native library project using CMake:


  • Create a folder named jniLibs under your app module's src/main folder.



  • Create a subfolder named cpp under the jniLibs folder.



  • Create a file named CMakeLists.txt under the jniLibs/cpp folder.



  • Edit the CMakeLists.txt file and add the following content:



# Set the minimum version of CMake required cmake_minimum_required(VERSION 3.10.2) # Set the name of your native library project project("my-native-lib") # Add your native source files add_library(my-native-lib SHARED my-native-lib.cpp) # Find and link the log library find_library(log-lib log) target_link_libraries(my-native-lib $log-lib)


  • Create a file named my-native-lib.cpp under the jniLibs/cpp folder.



  • Edit the my-native-lib.cpp file and add the following content:



# # Include the JNI header file #include


# Include the Android log header file #include


# Define a macro for logging #define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "my-native-lib", __VA_ARGS__)) # Define a native method that returns a string extern "C" JNIEXPORT jstring JNICALL Java_com_example_mynativelib_MainActivity_stringFromJNI( JNIEnv* env, jobject /* this */) LOGI("Hello from native code"); std::string hello = "Hello from C++"; return env->NewStringUTF(hello.c_str());


Congratulations, you have successfully created a native library project using CMake!


How to link your native library to your app module




To link your native library to your app module, you need to edit your app module's build.gradle file and add the following content:


android ... # Enable CMake support externalNativeBuild cmake path "src/main/jniLibs/cpp/CMakeLists.txt" version "3.10.2" # Specify the ABIs that you want to support defaultConfig ... externalNativeBuild cmake abiFilters "armeabi-v7a", "arm64-v8a", "x86", "x86_64"


After editing the build.gradle file, sync your project with Gradle f


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