You probably want to use NumberFormat.getCurrencyInstance(). This will return a NumberFormat object that uses the standard currency representation for your default Locale (or optionally, the one you pass in).

To right justify, you can use String.padLeft().

Example:

def formatter = java.text.NumberFormat.currencyInstance
def values = [0, 100000000, 9123123.25, 10.20, 1907.23]
def formatted = values.collect  { formatter.format(it) }
def maxLen = formatted*.length().max()
println formatted.collect { it.padLeft(maxLen) }.join("\n")

//output
          100,000,000.00
  10.20
      $1,907.23

You cannot parse it without knowing what the user will use as decimal separator, grouping separator, ... . For example if I type 1,250 you do not know whether I mean one thousand two hundred fifty (1,250.00), or one point two hundred fifty (1.250) . That's why the NumberFormat/DecimalFormat class of Java allows you to specify the grouping and decimal separator.

What you could do is hoping that the user inputs his values using the conventions corresponding to his Locale settings, and use the

NumberFormat.getInstance( Locale )

with the current Locale of the JVM.

Note: with the NumberFormat you can also parse a currency. See NumberFormat#getCurrencyInstance