java中的Double型加减乘除

import java.math.BigDecimal;

public class Arith {
private static final int DEF_DIV_SCALE = 10;

/**
* * 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 new Double(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 new Double(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 new Double(b1.multiply(b2).doubleValue());
}

/**
* * 两个Double数相除 *
* 
* @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 new Double(b1.divide(b2, DEF_DIV_SCALE, BigDecimal.ROUND_HALF_UP)
     .doubleValue());
}

/**
* * 两个Double数相除，并保留scale位小数 *
* 
* @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 new Double(b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue());
}
}