Android Studio is Google's official integrated development environment (IDE) for Android app development. Since its first stable release in 2014, Android Studio has grown in popularity and has replaced Eclipse as the IDE of choice for Android developers. Although some of the OpenCV documentation still contains outdated tutorials on Android development in Eclipse, nowadays, the OpenCV Android library and Android sample projects are primarily intended for use with Android Studio, instead.
Google provides a good cross-platform tutorial on Android Studio installation at https://developer.android.com/studio/install. Follow the part of the tutorial that is relevant to your operating system.
Download the latest version of the OpenCV Android pack from https://opencv.org/releases.html. Unzip it to any destination, which we will refer to as <...