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DigiTransit

This is an app for querying the DigiTransit GraphQL API in Finland and having some fun with it.

First of all, let me refer you to a YouTube channel AndroidFactory, which has immensely helped me in my work: https://www.youtube.com/channel/UCafJ0J81ELiYJgJyd-yqrpQ

Please check it out, as it is a vast source of modern Android stuff, and the videos are extremely well laid out!

Note

This currently works only in Finland, but some other cities in Europe have also implemented the DigiTransit as their public transport API. Check out for them. Basically, if you're in a country which implements the DigiTransit API, in the simplest case, all you have to do is to change the GraphQL API query endpoint (which in this application is https://api.digitransit.fi/routing/v1/routers/finland/index/graphql )

The Application

In general, the app tries to follow MVVM architecture, although there are some deviances, which I am working on:

Overall architecture of the app

The app locates you (or your mobile, of course) and polls for all public transport stops near you. The locationing interval (in seconds) and search radius (in meters) are set in the Settings tab. Also the stop polling delay and the departures polling delay (in seconds) can be set by the user.

Settings

When selecting a particular stop from the list of nearby stops returned from the query, the app opens a new fragment to poll&show the next departures from that particular stop.

The app also shows all traffic alerts, grouped by the Feed of the alert, that is, by the area / public transport agency which has published this alert. Usually, these feeds refer to particular towns in the area of the country's public transport system.

Traffic alerts

Currently, the feeds in Finland seem to be HSL (Helsinki public transport), OULU (Oulu public transport) and tampere (Tampere public transport), but the app shows any and all additional alerts that might subscribe to the alert system in future.

Stops view

List of stops near you

The StopsFragment shows for all nearby stops the following information:

  • stop name
  • name of the parent station, if such exists (for example, Elielinaukio)
  • stop code (in Helsinki area, the code that's printed on the stop sign), colour coded based on the stop type
  • zone (related to the fare policy of a trip on some parts of Finland public transport)
  • patterns that use this stop
  • all possible next stops for all patterns that go via this stop, marked with "->"
  • distance (in meters) to the stop

Stop card symbol and colour are chosen based on whether the Stop is recognized as being a bus, tram, metro, train etc. stop. In Helsinki (HSL) area, this is very thoroughly implemented. In other areas, the Stop card is shown as gray, indicating that the type property of the stop has not been implemented yet in the API.

Departures view

Next departures from this stop

The DeparturesFragment shows more information on the Stop selected (for example all Patterns using this Stop), in addition with the information of the next departures from this Stop.

For each Departure, the following information is shown:

  • date of departure
  • time until departure. When preceded with a "~", the time is an estimate, based on fixed timetables
  • headsign of the transportation vehicle departing from the Stop

Note that when a departure from this stop is based on an estimate, the corresponding departure card is outlined in yellow. When a realtime estimate exists, based on a true current GPS location of the transport vehicle, the departure card in question is outlined in green.

ToDo

  • better network/query error info propagation through the MVVM layers. Currently the only way of detecting problems in network layer is to detect a NULL response in the UI. The app does survive the NULL returning, but currently only notifies the user about them with a very generic Toast message
  • more intelligence to polling of the nearby stops: currently, the polling interval is set by the user (default: 10 seconds) and it is a constant time interval. The polling interval should be made dependent on how much the user has moved from his/her last location
  • Android theming: a BIG issue!
  • string constants handling (too many hardcoded strings atm)
  • better handling of the patterns through this stop (maybe using Epoxy for this as well?)
  • indicating of the outbound and inbound patterns/stops (colour coding?)