A native Android app giving the user access to river locations and information
This project focuses on creating an Android application to connect the user with information about rivers in Colorado. This includes access to river flow rates, weather conditions, and sampling locations. Using information from the US Geological Survey, this application will be a useful resource for anglers or boaters who are looking for current conditions on Colorado rivers.
1) Mapping USGS river sampling locations using the Google Maps API
2) Reporting current flow rates (cfs) of rivers in Colorado using the USGS REST
web services
3) Reporting current and projected weather for the sampling locations using the
AccuWeather api
On opening the app, the first view shows a google map of Colorado with markers showing the 338 USGS river sampling stations in the state[2]. These points are generated from a csv available on the USGS website [1]. There is an action bar at the top with a menu option showing favorites and a map alignment button. The user is able to zoom in and out of the map, pan, and search by text to find the location that they are looking for.
The user will tap on the marker of their choice which will cause a bubble to pop up displaying the location’s name. If this is the location the user would like information for, they may click on the bubble which will take them to a new view window. This view window will display current flow rates in cfs for that station as well as current and projected weather for that station location.
While in this station view, the user will also have the option to tap a star which will assign the station as a ‘favorite.’ This will save the station in the favorites menu for easy access to that information. The user will be able to hit a back button to return to the map view.
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Mapping USGS river sampling locations using the Google Maps API
a. Each river sampling location will be shown with a pin on a map
b. The pin will be tap-able to show the name of the location and prompt the user if they would like more information in a new view
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Reporting current flow rates (cfs) of rivers in Colorado using the USGS REST web services
a. This will show the current flow rate of the river at the selected sampling station
b. This will be shown in the more information view
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Reporting current and projected weather for the sampling locations using the Open weather map api
a. This will show the current and predicted weather for the selected sampling station
b. This will be shown in the more information view
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Saving river sampling stations as favorites
a. The option to save as a favorite will be shown as a star in the more information view
b. The favorites list will persist between different sessions
The main activity of River Reporter is implemented using the Android Google Maps api. On opening the app, the user will see a familiar layout and color scheme of the Google Maps app. The GoogleMaps class is used to create a map fragment in the main xml file, override the onCreate, onResume, and onMapReady functions in the MapsActivity, call methods for marker creation, and move the camera.
The action bar was created by extending AppCompatActivity in the MapsActivity. The menu was added using a menu view and overriding the onCreateOptionsMenu and onOptionsItemSelected methods.
The search bar was implemented using an EditText field view with a setOnEditorActionListener which is initialized when the map is created. The text entered into the search bar is then passed into Android’s geocoder library as a getFromLocationName search. The markers are placed during the onMapReady method using data from a local csv. The csv file was downloaded from the US Geological Survey’s website and contains information for 337 Colorado rivers[3]. The csv is kept in the asset folder of the app and read into an River object (using the CSVReader class) then placed in an ArrayList. It is then placed on the map as a marker using the longitude, latitude, and name.
Once an area of interest is chosen by panning or by searching, the user may tap on the markers in the area to see the names of the rivers. These names are the exact titles used by the USGS for cataloging their sampling data. Because the only information stored in the markers are the longitude, latitude, and name; I have implemented a search method which takes the selected marker’s name and scans the full ArrayList to find the corresponding River object. This River object contains the id which is necessary for making api calls.
The title above the marker is programmed with an on click listener which will open the dialog fragment showing that river’s current information. The results of each api call are passed into the dialog fragment constructor as objects. The information is then assigned to each text view as the fragment is constructed. The star in the top right is a toggle button which will add the river to the favorites list when selected and the fragment is closed, or remove the river from the favorites list when unselected and the fragment is closed. Adding a river to the favorites list involves inserting it into a favorite rivers ArrayList and a SQLite database.
To decrease the likelihood of returning null values for the discharge and weather, the api calls to the USGS api and AccuWeather api[4] are made once the user clicks on the marker to display the river’s name. Volley is used to create the request and add it to the request queue. Both api’s return JSON objects which are then parsed for the flowrate and weather forecasts. The call to the USGS is a single api call which does not require an api key, only a river ID. The AccuWeather call requires an api key as well as a two sequential api calls. The first is a call using the latitude and longitude which returns a location key. That location key must then be passed into the second request for the 5 day forecast. The calls were made synchronous to avoid returning null values for the 5 day forecast. The days of the week were obtained using the java.time.LocalDate and java.time.DayOfWeek libraries. The LocalDate object is found using LocalDate.now() for the current day and 4 days in the future. That LocalDate object is then converted into a day of the week using the getDayOfWeek() function which returns a day of week object.
Opening the menu and selecting favorites will then open the Favorite Rivers dialog fragment. These rivers are loaded each time a new river is added to the favorites list and each time the application is started. The view is created using a recycler view and River adapter. Each river also has an onClickListener which will produce its current dialog fragment when clicked.
To avoid returning null values in the single river dialog fragment, the api calls are made for each river as soon as the Favorite Rivers dialog fragment is opened. The results of each call are stored in separate ArrayLists and are then assigned to the view once a river is clicked. This will produce an identical dialog fragment to the one seen using the markers, except the star will be selected.
An interesting problem I ran into while implementing the SQLite database is that the id field, a string of 8 - 15 digits, would be converted to scientific notation each time it was stored in the database. This is an issue because many of the id’s begin with leading 0’s which were removed during the conversion causing their api calls to fail. While I was unable to find a way to stop the scientific notation conversion, I implemented a work around which pulls the id from the original ArrayList River object and uses that id to make the api call. The downside to this workaround is that it requires a for loop which could slow down the program in the event that the user has created an extremely large favorites list.
Sources: [1] https://maps.waterdata.usgs.gov/mapper/nwisquery.html?URL=https://waterdata.usgs.g ov/co/nwis/current?type=flow&group_key=basin_cd&site_no_name_select=siteno&form at=sitefile_output&sitefile_output_format=xml&column_name=agency_cd&column_nam e=site_no&column_name=station_nm&column_name=site_tp_cd&column_name=dec_l at_va&column_name=dec_long_va&column_name=agency_use_cd [2]https://developers.google.com/android/reference/com/google/android/gms/maps/Goo gleMap [3]https://waterservices.usgs.gov/rest/DV-Service.html [4]https://developer.accuweather.com/apis