保留两位小数

方案一

        Double totalSaleAmount = 4.174558045899999E7;
        DecimalFormat df = new DecimalFormat("#.##");
        System.out.println("df.format(totalSaleAmount) = " +     df.format(totalSaleAmount)); 

方案二

Double totalSaleAmount = 4.174558045899999E7;
NumberFormat percentInstance = NumberFormat.getPercentInstance();
percentInstance.setMinimumFractionDigits(2);
Double a = percentInstance.format(totalSaleamount);
System.out.println(a);

结果图