Geotools solution to read shapefile in EPSG3035 to get long / lat in WGS84?

Question

The shapefile coordinates are in EPSG3035, and I need to read them in regular long lat coordinates.

How can I do that with Geotools?

My code, without any conversion at the moment:

ShapefileDataStore dataStore = new ShapefileDataStore(file.toURL());
ContentFeatureSource featureSource = dataStore.getFeatureSource();
ContentFeatureCollection featureCollection = featureSource.getFeatures();
SimpleFeatureIterator iterator = featureCollection.features();

while (iterator.hasNext()) {
   SimpleFeature feature = iterator.next();
   Collection<Property> properties = feature.getProperties();
   etc...
}

Thanks!

Answer 1

Not tested, but so it should work. See my comments inline:

ShapefileDataStore dataStore = new ShapefileDataStore(file.toURL());
ContentFeatureSource featureSource = dataStore.getFeatureSource();
ContentFeatureCollection featureCollection = featureSource.getFeatures();
SimpleFeatureIterator iterator = featureCollection.features();

// get dynamically the CRS of your data:
SimpleFeatureType schema = featureSource.getSchema();
CoordinateReferenceSystem sourceCRS = schema.getCoordinateReferenceSystem();

// OR fallback to hardcoded 3035 if the above fails:
// CoordinateReferenceSystem sourceCRS = CRS.decode("EPSG:3035")

CoordinateReferenceSystem targetCRS = CRS.decode("EPSG:4326") // the coordinates system you want to reproject the data to
// define a MathTransform object
MathTransform transform = CRS.findMathTransform(sourceCRS, targetCRS);


while (iterator.hasNext()) {
   SimpleFeature feature = iterator.next();
   Collection<Property> properties = feature.getProperties();

   // get the geometry of the actual feature
   Geometry sourceGeometry = feature.getDefaultGeometry()
   // transform the geometry and save it in a new variable
   Geometry reprojectedGeometry = JTS.transform(sourceGeometry, transform)
   // set the reprojected geometry as the geometry of the actual feature
   feature.setDefaultGeometry(reprojectedGeometry)
   // .....
}

For more info see this tutorial: Geometry CRS Tutorial

Answer 2

    ShapefileDataStore SHPdataStore = new ShapefileDataStore(shpFile.toURI().toURL()); 
    ContentFeatureSource featureSource = SHPdataStore.getFeatureSource();
    ContentFeatureCollection featureCollection = featureSource.getFeatures();
    SimpleFeatureType schema = featureSource.getSchema();
    MathTransform transform = null;
    if(schema.getCoordinateReferenceSystem() != null) {
        CoordinateReferenceSystem sourceCRS = schema.getCoordinateReferenceSystem();
        CoordinateReferenceSystem targetCRS = CRS.decode(Constants.EPSG4326);
        
        transform = CRS.findMathTransform(sourceCRS, targetCRS, true);
    } 
   
    try (SimpleFeatureIterator iterator = featureCollection.features()) {
        SimpleFeature sfeature;
   
        if(schema.getCoordinateReferenceSystem() != null) {
         
            while (iterator.hasNext()) {
                sfeature = iterator.next();
                System.out.println(sfeature.getDefaultGeometry());
                sfeature.setDefaultGeometry(JTS.transform((org.locationtech.jts.geom.Geometry)sfeature.getDefaultGeometry(), transform));
                features.add(sfeature);
              }
        }
       
      } finally {
          SHPdataStore.dispose();
      }

Don't forgot to use try block for SimpleFeatureIterator and also to dispose the store otherwise you will face issue when running for multiple iteratble inputs.