private static LinearRing checkLineString(Geometry geometry) throws IllegalArgumentException {
        if (geometry instanceof LinearRing) {
            return (LinearRing) geometry;

        } else if (geometry instanceof LineString) {
            LineString lineString = (LineString) geometry;
            if (lineString.isClosed()) {
                return geometry.getFactory().createLinearRing(lineString.getCoordinateSequence());
            } else {
                throw new IllegalArgumentException("The linestring must be closed.");
            }
        } else  {
            throw new IllegalArgumentException("Only support linestring.");
        }
    }
private static LinearRing checkLineString ( Geometry geometry ) throws IllegalArgumentException { if ( geometry instanceof LinearRing ) { return ( LinearRing ) geometry ; } else if ( geometry instanceof LineString ) { LineString lineString = ( LineString ) geometry ; if ( lineString . isClosed ( ) ) { return geometry . getFactory ( ) . createLinearRing ( lineString . getCoordinateSequence ( ) ) ; } else { throw new IllegalArgumentException ( "The linestring must be closed." ) ; } } else { throw new IllegalArgumentException ( "Only support linestring." ) ; } }
Check if a geometry is a linestring and if its closed.

@param geometry
@return
@throws IllegalArgumentException