XStream + Converter + double no format BR

public class DoubleConverter implements Converter {

        private Locale locale;

        public DoubleConverter(Locale locale) {
                super();
                this.locale = locale;
        }

        public boolean canConvert(Class clazz) {
                return double.class.isAssignableFrom(clazz);
        }

        public void marshal(Object value, HierarchicalStreamWriter writer,
                        MarshallingContext context) {
                
                Double valor = (Double) value;
                                       
                NumberFormat nf;
                Locale ptBR = new Locale ("pt", "BR");
                nf  = new DecimalFormat ("######.00", new DecimalFormatSymbols (ptBR));
                
                writer.setValue(nf.format(valor));
        }

        public Object unmarshal(HierarchicalStreamReader reader,
                        UnmarshallingContext context) {
                
                double valor;
                NumberFormat nf;
                Locale ptBR = new Locale ("pt", "BR");
                nf  = new DecimalFormat ("######.00", new DecimalFormatSymbols (ptBR));
                
                try {
                        valor = nf.parse(reader.getValue()).doubleValue();                        
                } catch (ParseException e) {
                        throw new ConversionException(e.getMessage(), e);
                }
                return valor;
        }

}