[Java] RoundingMode 四舍五入

BigDecimal   i = (value) .setScale(2, RoundingMode.    MODE);

MODE :
ROUND_UP : away from 0         |<------------0------------->|
ROUND_DOWN : close to 0         |------------>0<-------------|

ROUND_CELLING :  to + infinity         |------------->|
ROUND_FLOOR :  to  - infinity            |<------------|


HALF_UP :   0.5 to 1  0.4 to 0       |<------------0.4 0.5------------->|
HALF_DOWN :   0.6 to 1  0.5 to 0       |<------------0.5 0.6------------->|

HALF_EVEN :  depends the value 5
                           ex : 11.4 ->11; 11.51->12;  
                                  11.503->12 (1 is impaired number)  ; 12.503-> 12 (2 is paired)
                                  11.6 -> 12