How to add a JAR file to a C++ Qt Widgets for Android project?

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Qt Creator uses the android deployment tool which copies certain files to the Android package. You can specify the package directory in your CMakeLists.txt file with:

if (ANDROID)
     set(ANDROID_PACKAGE_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/android")
endif()

You can create this directory along with template files in android by clicking “Create Templates” under Projects Mode (Ctrl+Five), “Build Steps” in “Build Android APK”.

In the “android” directory you can specify which JAR files to bundle in “build.gradle”, similar to the following:

dependencies {
    compile files('path/local_dependency.jar')
}

That was taken from https://riptutorial.com/gradle/example/8349/add-a-local-jar-file-dependency