bigdecimal解决小数间的加减乘除

public class bigdecimal {
    public static BigDecimal div(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.divide(b2,2,BigDecimal.ROUND_HALF_UP);//四舍五入两位小数
    }
}//除法的例子