bigdecimal保留兩位小數

public class test1_format {
public static void main(String[] args) {
BigDecimal decimal = new BigDecimal("1.12345");
System.out.println(decimal);
BigDecimal setScale = decimal.setScale(4,BigDecimal.ROUND_HALF_DOWN);
System.out.println(setScale);

BigDecimal setScale1 = decimal.setScale(4,BigDecimal.ROUND_HALF_UP);
System.out.println(setScale1);
}
}
1234567891011

參數定義

ROUND_CEILING
Rounding mode to round towards positive infinity.
向正無窮方向舍入

ROUND_DOWN
Rounding mode to round towards zero.
向零方向舍入

ROUND_FLOOR
Rounding mode to round towards negative infinity.
向負無窮方向舍入

ROUND_HALF_DOWN
Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round down.
向（距離）最近的一邊舍入，除非兩邊（的距離）是相等,如果是這樣，向下舍入, 例如1.55 保留一位小數結果為1.5

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（距離）最近的一邊舍入，除非兩邊（的距離）是相等,如果是這樣，如果保留位數是奇數，使用ROUND_HALF_UP ，如果是偶數，使用ROUND_HALF_DOWN

ROUND_HALF_UP
Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round up.
向（距離）最近的一邊舍入，除非兩邊（的距離）是相等,如果是這樣，向上舍入, 1.55保留一位小數結果為1.6

ROUND_UNNECESSARY
Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.
計算結果是精確的，不需要舍入模式

ROUND_UP
Rounding mode to round away from zero.
向遠離0的方向舍入