java 4舍5入

 

    /**
     * @Dscription: scale，保留幾位小數點 molecular 分子，denominator 分母
     * @Author: zyn
     * @Date: 2021/7/27
     */
    private static BigDecimal round(double molecular,double denominator,int scale){
        double total = (molecular * 100.0) / denominator;
        double total2 = new BigDecimal(total).setScale(scale, BigDecimal.ROUND_HALF_UP).doubleValue();
        return new BigDecimal(total2);
    }
    /**
     * @Dscription: scale，保留幾位小數點 v，需要操作的數
     * @Author: zyn
     * @Date: 2021/7/27
     */
    private static BigDecimal round(double f,int scale){
        return new BigDecimal(f).setScale(scale, RoundingMode.UP);
    }