Creating an App

Making icons for your app
- A launcher icon is a graphic that represents your application on the device's Home screen and in the Launcher window.
  - The icons live in the res/mipmap directory, as referenced from the application element in the manifest.
  - You can provide icons for each of the densities, but you can get away with only an extra high density icon.
- Image Asset Studio
  - Follow the instructions in the Andriod documentation
- Read the icon design guidelines.
Building an APK
- The Android system requires that all installed applications be digitally signed with a certificate whose private key is held by the application's developer.
- When exporting an APK the application is compiled in release mode, and you have to sign the .apk with a private key.
- It is recommended that you sign all your apps with the same certificate, and that you make the key valid for at least 25 years.
- See the Android web pages about signing an application
- An alternative, when deploying to Google Play, is to create a bundle. This defers APK generation and signing to Google Play ... so easy.
- See the Android web pages about bundles.
- When developing and testing Android Studio does this for you with a known keystore and key, in $HOME/.android/debug.keystore. This certificate is valid for 365 days.
- Use the "Build->Build Bundle(s) / APK(s)->Build APK(s)" feature of Android Studio, which will guide you through the process.
Versioning
- Apps can have version numbers and version names
- The values are set in build.gradle (Module ...)
- The versionCode is a positive integer used to determine if one version is more recent than another, with higher numbers indicating more recent versions. This is not shown to users.
- The versionName is a string used as the version number shown to users.
- For example ...
```
    defaultConfig {
        applicationId "edu.miami.cs.geoff.hellobutton"
        minSdk 23
        targetSdk 31
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    } 
```
- Read more in the Android documentation