java中double型數據的加減乘除

public class Arith {
    private static final int DEF_DIV_SCALE = 10;
    
    /**
     * 兩個Double數相加
     * @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();
    }
    
    /**
     * 兩個Double數相減
     * @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();
    }
    
    /**
     * 兩個Double數相乘
     * @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();
    }
    
    /**
     * 兩個Double數相除
     * @param v1
     * @param v2
     * @return Double
     */
    public static Double div(Double v1,Double v2){
        BigDecimal b1 = new BigDecimal(v1.toString());
        BigDecimal b2 = new BigDecimal(v2.toString());
        return b1.divide(b2,DEF_DIV_SCALE,BigDecimal.ROUND_HALF_UP).doubleValue();
    }
    
    /**
     * 兩個Double數相除，並保留scale位小數
     * @param v1
     * @param v2
     * @param scale
     * @return Double
     */
    public static Double div(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(v1.toString());
        BigDecimal b2 = new BigDecimal(v2.toString());
        return b1.divide(b2,scale,BigDecimal.ROUND_HALF_UP).doubleValue();
    }

}