Create geotools MultiPoint from java Collection

Question

I would like to create a GeoJSON containing a MultiPoint from a list of WGS coordinates in my custom format (say MyLonLat). I wanted to use geotools library to simplify this, but I can't find a nice and easy way to do this. One can create a MultiPoint from Coordinate[] or Point[] or CoordinateSequence, but not regular Java Collection, like List.

I found that GeometryFactory has method toGeometryArray, which can convert my list into Geometry[] (like Point[]). The problem is, that Point is not as simple a Coordinate so converting MyLonLat to Point requires implementing methods that I don't need.

Answer 1

The obvious way to solve this is to make your MyLatLon class extend Point with something like this:

public class BuildMultiPoints {
  static GeometryFactory GF = new GeometryFactory();
  public static void main(String[] args) {
    BuildMultiPoints me = new BuildMultiPoints();
    ArrayList<MyLonLat> points = new ArrayList<>();
    MyLonLat myLonLat = me.new MyLonLat(90.0, 0.0);
    points.add(myLonLat);
    points.add(me.new MyLonLat(50.0, 50.0));
    
    MultiPoint mp = GF.createMultiPoint(points.toArray(new MyLonLat[] {}));
    System.out.println(mp);
  }

  public class MyLonLat extends Point {
    public MyLonLat(double lat, double lon) {
      super(CoordinateArraySequenceFactory.instance().create(new Coordinate[] { new Coordinate(lat, lon) }), GF);
    }

    public MyLonLat(CoordinateSequence coordinates, GeometryFactory factory) {
      super(coordinates, factory);

    }

  }
}

If you are unable to do that then the next best option would be to store a Point inside the MyLonLat and delegate to that. Then you can go through the list extracting the points to build your multipoint.