Hello World Toast
It may very well be the simplest Android app. Works even on Android 1.0! All it does is display the famous Hello World! text in a toast - the familiar Android small popup used to show quick messages to the user. Then the app closes, even before starting... :-)
Overview
"Hello World" programs are pretty famous, even if all they do is write "Hello World!" on the screen. When learning a new programming language or platform, starting with such a simple program has become a tradition.
Hello World Toast is a standard Android app, that can be installed on any Android device, and started from the Apps or Home Screen. All it does is display the famous "Hello World!" text in a toast - the familiar Android small popup used to show quick messages to the user. Then the app closes, even before starting. That's it!
(However, Hello World Toast may be useful if you need to show someone how a real Android toast looks like.)
Hello World Toast is tiny (only 23k!), and runs on any Android smartphone, tablet, or device. It runs on the latest Android versions, and even on the oldest versions, starting with Android 1.0!
Open Source
Hello World Toast is free and doesn't contain any advertisements. It contains no permissions, either, so you don't have to worry about your privacy being compromised.
It's also open source. The project is hosted on GitHub and licensed under the MIT license. I look forward to your feedback or contributions!