Closing shapefile using org.geotools.data.shapefile.ShapefileFeatureReader gives warning?

Question

When working with shapefiles, i get this "warning"

    WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.ShapefileFeatureReader finalize
WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.ShapefileFeatureReader finalize
WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.ShapefileFeatureReader finalize
WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.ShapefileFeatureReader finalize
WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.ShapefileFeatureReader finalize
WARNING: There is code leaving shapefile readers unclosed, this might result in file system locks not being cleared. File is: chranene_uzemi_cr
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.files.ShpFiles logCurrentLockers
SEVERE: The following locker still has a lock: read on file:/F:/Škola/test_data/lesy_cr.shp by org.geotools.data.shapefile.shp.ShapefileReader
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.files.ShpFiles logCurrentLockers
SEVERE: The following locker still has a lock: read on file:/F:/Škola/test_data/lesy_cr.shx by org.geotools.data.shapefile.shp.IndexFile
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.files.ShpFiles logCurrentLockers
SEVERE: The following locker still has a lock: read on file:/F:/Škola/test_data/lesy_cr.dbf by org.geotools.data.shapefile.dbf.DbaseFileReader
Dub 08, 2018 11:23:13 ODP. org.geotools.data.shapefile.files.ShpFiles logCurrentLockers

But the project is build after that and i get results what i need. Not sure where is the problem. I am disposing datastore at the end but it dosnt seems to work.

String overlayPolygons(String shapeFileURL) throws IOException {

String areas = "Object : Area of overlay";

ShapefileDataStore sfds;
sfds = new ShapefileDataStore(new URL("file:///F:\\Škola\\test_data\\lesy_cr.shp"));

SimpleFeatureSource fs;
fs = sfds.getFeatureSource("lesy_cr");

ShapefileDataStore sfds2;
sfds2 = new ShapefileDataStore(new URL("file:///F:\\Škola\\test_data\\chranene_uzemi_cr.shp"));

SimpleFeatureSource fs2;
fs2 = sfds2.getFeatureSource("chranene_uzemi_cr");

SimpleFeatureIterator sfi = fs.getFeatures().features();
double sum = 0;
while (sfi.hasNext()) {
    SimpleFeature sf = sfi.next();
    MultiPolygon mp2 = (MultiPolygon) sf.getDefaultGeometry();
    Polygon p2 = (Polygon) mp2.getGeometryN(0);

    SimpleFeatureIterator sfi2 = fs2.getFeatures().features();
    while (sfi2.hasNext()) {
        SimpleFeature sf2 = sfi2.next();
        MultiPolygon mp3 = (MultiPolygon) sf2.getDefaultGeometry();
        Polygon p3 = (Polygon) mp3.getGeometryN(0);
        Geometry p4 = p2.intersection(p3);
        if (p4.getArea() != 0) {
            sum += p4.getArea();
            areas = areas + "\n" + p4.getArea()+ " : " + p2.getArea() + " : " + p3.getArea();
        }

    }
}

sfds.dispose();
sfds2.dispose();


return "Objects found: " + areas + "\nTotal sum: " + sum;
}

Answer 1

You must close the iterators sfi and sfi2 after their respective loops.

SimpleFeatureIterator sfi = fs.getFeatures().features();
double sum = 0;

while (sfi.hasNext()) {
    SimpleFeature sf = sfi.next();
    MultiPolygon mp2 = (MultiPolygon) sf.getDefaultGeometry();
    Polygon p2 = (Polygon) mp2.getGeometryN(0);

    SimpleFeatureIterator sfi2 = fs2.getFeatures().features();
    while (sfi2.hasNext()) {
        SimpleFeature sf2 = sfi2.next();
        MultiPolygon mp3 = (MultiPolygon) sf2.getDefaultGeometry();
        Polygon p3 = (Polygon) mp3.getGeometryN(0);
        Geometry p4 = p2.intersection(p3);
        if (p4.getArea() != 0) {
            sum += p4.getArea();
            areas = areas + "\n" + p4.getArea()+ " : " + p2.getArea() + " : " + p3.getArea();
        }
    }
    sfi2.close();
}
sfi.close();

sfds.dispose();
sfds2.dispose();