The app "Gfrör.li" displays current water temperatures of Swiss lakes and rivers in dozends of different locations. Ideal for temperature-sensitive people that still like swimming outside when the temperature is sufficiently high!
The data displayed comes from our community-operated LoRaWAN based measuring stations and is updated multiple times per hour. Additionally, we integrate data from public measuring stations (like from the Swiss FOEN) when the license permits us to do so. You can find more information about the project at gfrör.li.
First, create a file containing the API keys. You can use either:
app/secrets.properties(project-specific, takes precedence)~/.config/gfroerli-android/secrets.properties(global fallback)
For example:
echo "gfroerli_api_key_public=<VALUE>" >> app/secrets.properties
echo "mapbox_access_token=<VALUE>" >> app/secrets.properties
Then, build the app with Gradle:
./gradlew build
To install the app to your device:
./gradlew installDebug
(Alternatively, do all that stuff through Android Studio.)
To build a release APK, add the following entries to the secrets.properties
file (see above):
keystoreFile=release.keystore
keystorePassword=***
keyAlias=the-key-alias
keyPassword=***
Make sure that the keystoreFile path exists. Then run:
./gradlew clean assembleRelease
The app includes an Android Auto integration that shows nearby water temperatures and lets you navigate to a sensor location.
Note that Google requires apps built with the Android for Cars App Library to be installed through Google Play: If the app was installed through Accrescent, GitHub or IzzyOnDroid, it will not show up in Android Auto. Unlike for media apps, this cannot be bypassed with the "Unknown sources" developer setting (docs).
For development, test the car app with the Desktop Head Unit (DHU), which does run sideloaded builds. To test in a real car, the app must be installed through Google Play (e.g. from the internal testing track).
- If you use the Android Studio emulator, make sure to enable hardware graphics acceleration (Edit > Additional Settings > Graphics acceleration > Hardware), otherwise the sensors won't render correctly on the map.
The translations can be found in the XML resource files at
app/src/main/res/values-<qualifier>/strings.xml.
We prefer informal, simple language. For all languages, the Swiss variety
should be used (as indicated by the -rCH regional qualifier).
Copyright © 2016–2026 Coredump Hackerspace.
Licensed under the GPLv3 or later, see LICENSE.txt.