Apps Script offers the ability to publish completed web apps to the Chrome Web Store for distribution, but usability relies heavily on the app’s ability to communicate with external applications. As an example, if you receive an email with attachments on a mobile device, you could easily use an Apps Script-based add-on to auto-save those attachments to Google Drive.
This function relies on the external application’s ability to communicate with the Apps Script project, which uses Google’s Execution API. In this Quickstart Guide on Google Developers blog, followers are shown how to build a simple Android application that makes calls to the Apps Script Execution API.
Followers will need an Android Studio SDK 1.2 or later, Android SDK packages for API 23 or later, and a target Apps Script for the API to call. Once you have acquired an SHA1 fingerprint, enable the Execution API and prepare a new Android project. Using the code provided, simply set up the sample and then run the app, all of which should be accomplished in around 10 minutes.