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();
}