Not an April fool's joke, my first Android app is now available for download from the Play Store.
Find-A-Word finds English words that match a given letter pattern or anagram. It contains a huge dictionary of over 500,000 word forms packed into a tiny 3MB download. It also searches super-fast thanks to its use of a finite-state automaton.
Find-A-Word is also a web site of mine: findaword.net, so I used this as a way to learn how to build apps. Over the years I've tried a number of toolkits designed to make app development "easier", but mostly they are a pain to use. A couple of years ago I experimented with Cordova, a toolkit that allows you to write apps in HTML, CSS and Javascript for multiple mobile platforms. It comes with a library (Phonegap) that allows you to access the phone hardware: GPS, compass, accelerometer, etc. However because it is cross-platform it is also least-common-denominator: you get the most basic access supported by all devices. I found it very unhelpful when trying to build an app that recorded high-quality audio. More recently I looked at a toolkit called Crosswalk, which is a cut-down version of Cordova that bundles a complete web browser with your own code. This means that you can rely on the browser environment where your app is running without having to tailor your code to Android or iOS, etc. This worked OK but (i) the downloads were huge (>20Mb) and (ii) the project stopped being developed in 2017. For the Find-A-Word app, I've switched over to building on top of Android WebView, this is the web browser object found on all Android devices. With help from the many tutorial guides on the web (thank you Stack Overflow!) I was able to take my web site code and package it using Android Studio. I've learned a lot by attempting this. It's not so bad when you dive in.