double加减乘除

//四舍五入
    public static double toDecimal(Double num){
        if(Double.isNaN(num) || num == null){
            return 0;
        }
        return new BigDecimal(num).setScale(2, RoundingMode.HALF_UP).doubleValue();
    }

    /**
     * 两个double相除
     * @param v1
     * @param v2
     * @param scale
     * @return
     */
    public static double division(double v1, double v2, int scale) {
        if (scale < 0) {
            throw new IllegalArgumentException(
                    "The scale must be a positive integer or zero");
        }
        BigDecimal b1 = new BigDecimal(Double.toString(v1));
        BigDecimal b2 = new BigDecimal(Double.toString(v2));
        return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
    }
    /**
     * 两个Double数相加
     * @param v1
     * @param v2
     * @return Double
     */
    public static Double add (Double v1,Double v2){
        BigDecimal b1 = new BigDecimal(v1.toString());
        BigDecimal b2 = new BigDecimal(v2.toString());
        return b1.add(b2).doubleValue();
    }

    /**
      * 两个Double数相减
      * @param v1
      * @param v2
      * @return Double
      */
    public static Double sub(Double v1,Double v2){
        BigDecimal b1 = new BigDecimal(v1.toString());
        BigDecimal b2 = new BigDecimal(v2.toString());
        return b1.subtract(b2).doubleValue();
    }

    /**
     * 两个Double数相乘
     * @param v1
     * @param v2
     * @return Double
     */
    public static Double mul(Double v1,Double v2){
        BigDecimal b1 = new BigDecimal(v1.toString());
        BigDecimal b2 = new BigDecimal(v2.toString());
        return b1.multiply(b2).doubleValue();
    }