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_UP);
?}
?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_UP);
?}
?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_UP);
?}
?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_UP);
?}
?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();
?}
?
?public static void main(String[] args)throws Exception{
??System.out.println(divide(10, 3, 3, BigDecimal.ROUND_HALF_UP));
?}
}
