double 四舍五入并保留两位小数点

//方案一:
get_double = (double) (Math.round (result_value * 100) / 100.0)

//方案二:
DecimalFormat df = new DecimalFormat ("#.##");
get_double = Double.ParseDouble (df.format (result_value) );

//方案三:
get_double = Double.ParseDouble (String.format ("%.2f", result_value) );

//方案四:
BigDecimal bd = new BigDecimalresult_value();
BigDecimal bd2 = bd.setScale (2, BigDecimal .ROUND_HALF_UP);
get_double = Double.ParseDouble (bd2.ToString() );