关于BigDecimal.ROUND_HALF_UP与ROUND_HALF_DOWN

huim

都是四舍五入的意思，但有什么区别呢？

看了半天，单词都认识了，就是没弄明白，大侠们能不能用我们可爱的汉语表述一下？

ROUND_HALF_UP
Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up. Behaves as for ROUND_UP if the discarded fraction is >;= .5; otherwise, behaves as for ROUND_DOWN. Note that this is the rounding mode that most of us were taught in grade school

ROUND_HALF_DOWN
Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down. Behaves as for ROUND_UP if the discarded fraction is >; .5; otherwise, behaves as for ROUND_DOWN.

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ROUND_HALF_UP: 遇到.5的情况时往上近似,例: 1.5 ->;2
ROUND_HALF_DOWN : 遇到.5的情况时往下近似,例: 1.5 ->;1

BigDecimal a = new BigDecimal(1.5);
                System.out.println("down="+a.setScale(0,BigDecimal.ROUND_HALF_DOWN)+"\tup="+a.setScale(0,BigDecimal.ROUND_HALF_UP));
结果:down=1  up=2
看这个例子就明白了!

huim

也就是说，如果是四舍五入，必须得用 ROUND_HALF_UP ?