BigDecimal保留小数位

1
2
3
4
5
6
7
8
9
10
11
12
public class BigDecimalFormat {

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

BigDecimal scale2 = decimal.setScale(4, BigDecimal.ROUND_HALF_UP);
System.out.println(scale2);
}
}

BigDecimal.setScale()方法用于格式化小数点

1
2
3
4
5
setScale(1) 表示保留一位小数,默认用四舍五入方式
setScale(1, BigDecimal.ROUND_DOWN) 直接删除多余的小数位,如2.35会变成2.3
setScale(1, BigDecimal.ROUND_UP) 进位处理,2.35变成2.4
setScale(1, BigDecimal.ROUND_HALF_UP) 四舍五入,2.35变成2.4
setScale(1, BigDecimal.ROUND_HALF_DOWN) 五舍六入,2.35变成2.3

参数定义

  • ROUND_CEILING

Rounding mode to round towards positive infinity.
向正无穷方向舍入

  • ROUND_DOWN

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

  • ROUND_FLOOR

Rounding mode to round towards negative infinity.
向负无穷方向舍入

  • 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

  • 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

  • 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

  • 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

  • ROUND_UP

Rounding mode to round away from zero.
向远离0的方向舍入

Powered by AppBlog.CN     浙ICP备14037229号

Copyright © 2012 - 2020 APP开发技术博客 All Rights Reserved.

访客数 : | 访问量 :