GeoTools (Java) read properties from ESRI shapefile at specific coordinates

Question

This is my first time using GeoTools and I have a 3 simple things I need to get from .shp files which I'm reading with my program.

I need to know in specific coordinates (latitude/longitude).

Example: lat=58.85 lon=5.26 for 3 specific things:

1. Exclusive Economic Zone (EEZ)
2. FAO area
3. ICES statistical rectangle

I know that all of these properties are there, because tested the whole shapefile and it gave my these results:

EEZ<EEZ id=eez.232>=German Exclusive Economic Zone
EEZ<EEZ id=eez.233>=Azerbaijanis Exclusive Economic Zone
EEZ<EEZ id=eez.234>=Kazakh Exclusive Economic Zone

And same is for ICES rectangles:

ICESNAME<ICESNAME id=ices.11002>=26M8
ICESNAME<ICESNAME id=ices.11003>=27M8

It reads the whole shapefile, but I don't know how to read these 3 properties from specific coordinate.

My program code:

File file = new File(shapeDirectory + "ices.shp");

Map<String, Object> map = new HashMap<>();
map.put("url", file.toURI().toURL());

DataStore dataStore = DataStoreFinder.getDataStore(map);
String typeName = dataStore.getTypeNames()[0];

FeatureSource<SimpleFeatureType, SimpleFeature> source = dataStore.getFeatureSource(typeName);
Filter filter = Filter.INCLUDE; // ECQL.toFilter("BBOX(THE_GEOM, 10,20,30,40)")

SimpleFeatureType schema = source.getSchema();
String geomType = schema.getGeometryDescriptor().getType().getBinding().getName();
System.out.println(geomType);

    FeatureCollection<SimpleFeatureType, SimpleFeature> collection = source.getFeatures(filter);
    try (FeatureIterator<SimpleFeature> features = collection.features()) {
        while (features.hasNext()) {
            SimpleFeature feature = features.next();
            System.out.print(feature.getID());
            Property property = feature.getProperty("ICESNAME");
            System.out.println(property);
        }
    }
}

How to read all these 3 attributes (from 3 different shape files (fao/ices/eez)) at specific coordinates? The coordinate input will be decimal, but if someone knows, please provide me the degrees/minutes/seconds example too.

Answer 1

Basically you need a contains filter so that you get back the feature(s) which have a polygon that contains the point.

First, you need to know the name of the geometry attribute in your features:

Expression propertyName = filterFactory.property(features.getSchema()
            .getGeometryDescriptor().getName());

Then build a point p:

GeometryFactory fac = new GeometryFactory();
double lat = (Math.random() * 180.0) - 90.0;
double lon = (Math.random() * 360.0) - 180.0;
Point p = fac.createPoint(new Coordinate(lat, lon));

And then you need to build a filter with your point (p):

FilterFactory2 filterFactory = CommonFactoryFinder.getFilterFactory2(GeoTools
            .getDefaultHints());
Filter filter = filterFactory.contains(propertyName,
            filterFactory.literal(p));

And finally, fetch any features that match that filter:

SimpleFeatureCollection sub = features.subCollection(filter);

You then need to repeat those steps for each of your shapefiles for as many points as you need.

As for converting DMS to decimal degrees, this should do it:

public class DMSToDegrees {

  public static void main(String[] args) {
    System.out.println(DMSToDegrees.convert(37, 42, 17));
    System.out.println(DMSToDegrees.convert(89, 11, 15));
    System.out.println(DMSToDegrees.convert(-37, 42, 17));
  }

  static public double convert(int degrees, int minutes, double seconds) {
    float sign = Math.signum(degrees);
    double dmins = minutes+seconds/60.0;
    double deg = Math.abs(degrees) + dmins/60.0;
    return sign*deg;
  }
}