package cn.netkiller.example;
import java.math.BigDecimal;
public class Math {
public Math() {
// TODO Auto-generated constructor stub
}
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 double sub(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 double mul(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 double div(double v1, double v2) {
return div(v1, v2, 8);
}
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(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}
public static double round(double v, int scale) {
if (scale < 0) {
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}
BigDecimal b = new BigDecimal(Double.toString(v));
BigDecimal one = new BigDecimal("1");
return b.divide(one, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}
}
double amount = Double.parseDouble(value);
import java.text.NumberFormat;
import java.text.ParseException;
try {
Double num = (Double)NumberFormat.getInstance().parse("67.89%"); // 转换的结果是67.89
Double num2 = (Double)NumberFormat.getPercentInstance().parse("67.89%"); // 转换的结果是0.6789
System.out.println(num);
} catch (ParseException e) {
e.printStackTrace();
}
import java.text.NumberFormat;
import java.text.ParseException;
try {
NumberFormat percentInstance = NumberFormat.getPercentInstance();
percentInstance.setMaximumFractionDigits(2); // 保留小数两位
String format = percentInstance.format(0.81247); // 结果是81.25% ,最后一们四舍五入了
System.out.println(num);
} catch (ParseException e) {
e.printStackTrace();
}