The format you need is € #,###.00
, ,
means you use a grouping separator.
Then, you need a DecimalFormatSymbols
to specify the grouping symbol and the decimal symbol:
DecimalFormatSymbols symbols = new DecimalFormatSymbols();
symbols.setGroupingSeparator('\'');
symbols.setDecimalSeparator(',');
DecimalFormat decimalFormat = new DecimalFormat("€ #,###.00", symbols);
String prezzo = decimalFormat.format(number);
Result € 1'515,28