• NumberFormat : NOT Thread Safe
• DecimalFormat : NOT Thread Safe

NumberFormat nf = new DecimalFormat("#0.00");
 
NumberFormat nf = NumberFormat.getInstance();

• #0.00 : 0.00, 0.90, 10.92, 100.23 등의 형태

• formatting - In Java, can I use DecimalFormat to enter a dash (-) between numbers?
• DecimalFormatSymbols : Thread Safe 인지 여부가 확실치 않음.

DecimalFormatSymbols decimalFormatSymbols = new DecimalFormatSymbols();
decimalFormatSymbols.setGroupingSeparator('-');
DecimalFormat decimalFormat = new DecimalFormat("####,####", decimalFormatSymbols);
 
decimalFormat.format(123456789L); // 1-2345-6789