How to use Java's DecimalFormat for "smart" currency formatting?

Question

I'd like to use Java's DecimalFormat to format doubles like so:

#1 - 100 -> $100
#2 - 100.5 -> $100.50
#3 - 100.41 -> $100.41

The best I can come up with so far is:

new DecimalFormat("'$'0.##");

But this doesn't work for case #2, and instead outputs "$100.5"

Edit:

A lot of these answers are only considering cases #2 and #3 and not realizing that their solution will cause #1 to format 100 as "$100.00" instead of just "$100".

Answer 1

Does it have to use DecimalFormat?

If not, it looks like the following should work:

String currencyString = NumberFormat.getCurrencyInstance().format(currencyNumber);
//Handle the weird exception of formatting whole dollar amounts with no decimal
currencyString = currencyString.replaceAll("\\.00", "");

Answer 2

Use NumberFormat:

NumberFormat n = NumberFormat.getCurrencyInstance(Locale.US); 
double doublePayment = 100.13;
String s = n.format(doublePayment);
System.out.println(s);

Also, don't use doubles to represent exact values. If you're using currency values in something like a Monte Carlo method (where the values aren't exact anyways), double is preferred.

See also: Write Java programs to calculate and format currency