java中的四舍五入实现
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(v);
BigDecimal one = new BigDecimal("1");
return b.divide(one, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}
利用BigDecimal类中提供的除法。
BigDecimal | divide(BigDecimal divisor, int scale, int roundingMode) Returns a BigDecimal whose value is (this / divisor), and whose scale is as specified. |
参数：
static int | ROUND_HALF_DOWN Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down. |
static int | ROUND_HALF_EVEN Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor. |
static int | ROUND_HALF_UP Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up. |
so help me to get where i belong......i love u...forever....
评论