java精确数字计算

import java.math.BigDecimal;

public class MathExtend

{

//默认除法运算精度
private static final int DEFAULT_DIV_SCALE = 10;

public static double add(double v1, double v2)
{
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.add(b2).doubleValue();
}

public static String add(String v1, String v2)
{
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.add(b2).toString();

}

public static double subtract(double v1, double v2)
{

BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.subtract(b2).doubleValue();

}

public static String subtract(String v1, String v2)
{
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.subtract(b2).toString();

}

public static double multiply(double v1, double v2)
{
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.multiply(b2).doubleValue();
}

public static String multiply(String v1, String v2)
{
BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.multiply(b2).toString();
}

public static double divide(double v1, double v2)
{
return divide(v1, v2, DEFAULT_DIV_SCALE);
}

public static double divide(double v1,double v2, int scale)
{
return divide(v1, v2, scale, BigDecimal.ROUND_HALF_EVEN);
}

public static double divide(double v1,double v2,int scale, int round_mode){
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, round_mode).doubleValue();
}

public static String divide(String v1, String v2)
{
return divide(v1, v2, DEFAULT_DIV_SCALE);
}

public static String divide(String v1, String v2, int scale)
{
return divide(v1, v2, DEFAULT_DIV_SCALE, BigDecimal.ROUND_HALF_EVEN);
}

public static String divide(String v1, String v2, int scale, int round_mode)
{
if(scale < 0)
{
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}

BigDecimal b1 = new BigDecimal(v1);
BigDecimal b2 = new BigDecimal(v2);
return b1.divide(b2, scale, round_mode).toString();

}

public static double round(double v,int scale)
{
return round(v, scale, BigDecimal.ROUND_HALF_EVEN);
}

public static double round(double v, int scale, int round_mode)
{
if(scale<0)
{
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}

BigDecimal b = new BigDecimal(Double.toString(v));
return b.setScale(scale, round_mode).doubleValue();
}

public static String round(String v, int scale)
{
return round(v, scale, BigDecimal.ROUND_HALF_EVEN);
}

public static String round(String v, int scale, int round_mode)
{
if(scale<0)
{
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}

BigDecimal b = new BigDecimal(v);
return b.setScale(scale, round_mode).toString();

}

}