Função de format moeda brasileira

CurrencyFormat.java

public final class CurrencyFormat {
	public static String format(String valor) {
		Currency curr = Currency.getInstance(new Locale("PT", "br"));		
		char[] reversed = new StringBuilder(valor).reverse().toString().toCharArray();
		StringBuilder sb = new StringBuilder();
		int index = 0;
		for (char c : reversed) {
			if (index == curr.getDefaultFractionDigits()) {
				sb.append(",");				
			} else if (index == curr.getDefaultFractionDigits() + 3) {
				sb.append(".");
				index = curr.getDefaultFractionDigits();
			}
			sb.append(c);
			index++;
		}
		return curr.getSymbol() + " " + sb.reverse();
	}
}