Wadwaaier, Android app for dutch "Wadden" region

Wadwaaier Icon The original Wadwaaier is a publication by the dutch Waddenvereniging. It features around 100 cards of the animals and plants that live in the dutch Wadden region. Every card contains an illustration of a species, along with a short description.

Main screen

The mobile app has several features: browsing, searching, taking a picture, and defining favorites. An information screen is also present, allowing the Waddenvereniging to display any information they want.

At the bottom of the screen a banner is placed, of which the content and url are also specified in the backend.


All species are classified in categories (taxons). The browse screen shows these in a scrollable list, currently 7 categories. Clicking on a category shows a screen with all species in this category.


All species have a list of properties, like size, color and shape. Each of these properties have several values, the user can toggle values to narrow down the search.

When a value is toggled, the app calculates how many species possess all currently active values, and displays this. In the image it can be seen that there are 21 species whose shape ('Vorm') is oval.

The user could then for example go to the screen for the Color property, and select 'Yellow' to find there are 11 species both oval and yellow.

When a user is outside and finds an animal, this technique allows for rapid identification of the species.

Taking pictures

If a backfacing camera is present on the device, the main screen and the animal detail screen will show the option to take a picture. This is saved on the device's SD card for later viewing and sharing. The Waddenvereniging encourages users to send in their pictures of animals that were found.

Adding favorites

A species' detailscreen shows illustrations, a short description and buttons to take a picture, share and add to favorites (+). Favorites can be accessed from the main screen in a list.

Inner workings

The app retrieves data from a webserver maintained by WebIQ. Waddenvereniging employees can change the data in their CMS, and the app will occasionally retrieve this as a JSON in an IntentService. Internally the data is stored in a singleton, which gets updated when a change has been detected in the JSON. When this happens, a broadcast is sent, and any Activity which is registered to it will refresh its data.

The JSON contains all data and a timestamp, but a seperate timestamp is also available. This reduces data traffic. This timestamp is online like this:


In order to not require network access (for example outside in the Wadden), a default database is also supplied in the app itself.

Which species are selected as favorites is stored in a sqlite database.

Get it on Google Play