NumberFormatException maybe yes maybe no

I have to work on a test machine and when my work is complete and tested, I have to put it online for customers.

On these two machines my code doesn't work in different ways!

This part is the problem:

public void setQntaRiduAsDecimalQuantityString(String qntaRidu) {
try{
Double pippo=new Double(qntaRidu.replace(',','.'));
}
catch(NumberFormatException x)
{...}

On test machine i have String qntaRidu = 42,123 (with comma).
All goes ok and pippo gets 42.123

On "Online" machine the same code, and same value in qntaRidu , cast a NumberFormatException.

In java, is number format customizable ? (for example in Oracle you can localize your machine, so you can choose to have comma as decimal separator instead of dot.)

Thanks for help (i work with oc4j 10.1.3.3)