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  • BigDecimal 舍入模式(Rounding mode)介绍

    BigDecimal 舍入模式(Rounding mode)介绍

    在 java中, 四舍五入通过 BigDecimal 来实现。一定要注意:BigDecimal is Immutable。也就是跟String一样,对前一个的修改,比如setScale(), add()等都会返回一个新的BigDecimal.四舍五入舍入模式是 BigDecimal.ROUND_HALF_UP 

    BigDecimal定义了一下舍入模式,只有在作除法运算或四舍五入时才用到舍入模式,下面简单介绍,详细请查阅J2se API文档

    static int

    ROUND_CEILING

               Rounding mode to round towards positive infinity.

    向正无穷方向舍入

    static int

    ROUND_DOWN

               Rounding mode to round towards zero.

    向零方向舍入

    static int

    ROUND_FLOOR

               Rounding mode to round towards negative infinity.

    向负无穷方向舍入

    static int

    ROUND_HALF_DOWN

               Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.

    向(距离)最近的一边舍入,除非两边(的距离)是相等,如果是这样,向下舍入, 例如1.55 保留一位小数结果为1.5

    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.

    向(距离)最近的一边舍入,除非两边(的距离)是相等,如果是这样,如果保留位数是奇数,使用ROUND_HALF_UP ,如果是偶数,使用ROUND_HALF_DOWN

    static int

    ROUND_HALF_UP

               Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.

    向(距离)最近的一边舍入,除非两边(的距离)是相等,如果是这样,向上舍入, 1.55保留一位小数结果为1.6

    static int

    ROUND_UNNECESSARY

               Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.

    计算结果是精确的,不需要舍入模式

    static int

    ROUND_UP

               Rounding mode to round away from zero.

    向远离0的方向舍入

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  • 原文地址:https://www.cnblogs.com/carelesswords/p/3558839.html
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