import com.vividsolutions.jts.geom.GeometryFilter; //导入依赖的package包/类
/** */
public static Geometry flatten (GeometryCollection gc) {
    final List<Point> points = new LinkedList<Point>();
    final List<LineString> lines = new LinkedList<LineString>();
    final List<Polygon> polygons = new LinkedList<Polygon>();
    gc.apply(new GeometryFilter() {
            public void filter (Geometry geom) {
                if (geom instanceof Point) {
                    points.add((Point)geom);
                } else if (geom instanceof LineString) {
                    lines.add((LineString)geom);
                } else if (geom instanceof Polygon) {
                    polygons.add((Polygon)geom);
                }
            }
        });
    if (!polygons.isEmpty()) {
        return gc.getFactory().createMultiPolygon(GeometryFactory.toPolygonArray(polygons));
    } else if (!lines.isEmpty()) {
        return gc.getFactory().createMultiLineString(GeometryFactory.toLineStringArray(lines));
    } else {
        return gc.getFactory().createMultiPoint(GeometryFactory.toPointArray(points));
    }
}
 

import com.vividsolutions.jts.geom.GeometryFilter; //导入依赖的package包/类
public static void applyToInnerGeometries(final Polygon g, final GeometryFilter f) {
	final int holes = g.getNumInteriorRing();
	if (holes == 0)
		return;
	for (int i = 0; i < holes; i++) {
		g.getInteriorRingN(i).apply(f);
	}
}
 

import com.vividsolutions.jts.geom.GeometryFilter; //导入依赖的package包/类
@Override
public void apply(final GeometryFilter filter) {
	filter.filter(this);
}
 

import com.vividsolutions.jts.geom.GeometryFilter; //导入依赖的package包/类
void drawSimpleGeometry(final OpenGL gl, final Geometry geom) throws ExecutionException {
	geom.apply((GeometryFilter) (g) -> drawer.accept(g));
}
 

import com.vividsolutions.jts.geom.GeometryFilter; //导入依赖的package包/类
@Override
public void apply(GeometryFilter filter) {
	// Do nothing. This circle is not expected to be a complete geometry.		
}