public static void main(String[] args) {
String str="0";
BigDecimal bd = new BigDecimal(Double.parseDouble(str));
System.out.println(bd.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue());
System.out.println("=================");
DecimalFormat df = new DecimalFormat("#.00");
System.out.println(df.format(Double.parseDouble(str)));
System.out.println("=================");
System.out.println(String.format("%.2f", Double.parseDouble(str)));
System.out.println("=================");
NumberFormat nf = NumberFormat.getNumberInstance();
nf.setMaximumFractionDigits(2);
System.out.println(nf.format(Double.parseDouble(str)));
}