If you’re using Android Studio to build C++ application with NDK you might encounter following error during build:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformNativeLibsWithStripDebugSymbolForDebug'. ... Caused by: java.io.IOException: Cannot run program ".../Android/Sdk/ndk-bundle/toolchains/mips64el-linux-android-4.9/prebuilt/linux-x86_64/bin/mips64el-linux-android-strip": error=2, No such file or directory
The problem is caused by the upgrade of NDK in Android Studio to NDK v17. This version has a different structure of tools. It’s not compatible with Android Experimental Plugin v0.11.
The directory which should contain binary of tools contains just file NOTICE-MIPS64:
This mips64el-linux-android-4.9 directory exists to make the NDK compatible with the Android SDK's Gradle plugin, version 3.0.1 and earlier, which expects the NDK to have a MIPS64 toolchain directory.
The solution is to download NDK v16 from NDK older releases. Extract it and replace former ndk-bundle directory.
Commands for macOS or Linux users:
cd ~/Android/Sdk unzip ~/Downloads/android-ndk-r16b-linux-x86_64.zip mv ndk-bundle ndk-bundle-v17 mv android-ndk-r16b ndk-bundle
If you’re Windows user the location of NDK is typically in your profile AppData\Local\Android. Do not forget to unblock the ZIP after downloading (right click, Properties, Unblock, Ok)
Commands for Windows users:
cd ~\AppData\Local\Android\Sdk unzip ~\Downloads\android-ndk-r16b-windows-x86_64.zip mv ndk-bundle ndk-bundle-v17 mv android-ndk-r16b ndk-bundle
Start Android Studio. It should prompt you to update NDK. Do not confirm this request, it will replace NDK with v17. You should see the following screen in SDK Manager:
You can find related sample source code at GitHub in sdl2-android-example – branch gradle-4-using-android-experimental-plugin repository. Further articles about SDL2 and Android are available under the tag SDL2.
Since Google is moving away from Gradle Android Experimental plugin you might consider using Gradle 5 + CMake. The migration is relatively easy and it could save you the trouble of being stuck with old NDK. You need to create CMakeLists.txt instead of build.gradle for C/C++ parts of the code. Example of migration is at GitHub – sdl2-android-example – PR#6.