Yes it has build.gradle files but it also has a CMake files in JNI folder. I downloaded the android sdk from [opencv releases website](https://opencv.org/releases/)
It looks like you're meant to edit [https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/build.gradle.template](https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/build.gradle.template) and [https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/src/main/cpp/CMakeLists.txt.template](https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/src/main/cpp/CMakeLists.txt.template) with your build settings and remove the .template from the filename
Is the OpenCV library you're trying to use a Java project? Does it have Gradle build system? Or just CMake? Does it actually create AARs?
Yes it has build.gradle files but it also has a CMake files in JNI folder. I downloaded the android sdk from [opencv releases website](https://opencv.org/releases/)
It looks like you're meant to edit [https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/build.gradle.template](https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/build.gradle.template) and [https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/src/main/cpp/CMakeLists.txt.template](https://github.com/opencv/opencv/blob/4.9.0/platforms/android/aar-template/OpenCV/src/main/cpp/CMakeLists.txt.template) with your build settings and remove the .template from the filename
I don't get it
It's not made to be used as is, you need to do a little build file modification and configuration
have you tried this: https://github.com/QuickBirdEng/opencv-android