java BigDecimal

时间  2019-11-10
标签 java bigdecimal 栏目 Java 繁體版
原文   原文链接 
package com.qjx.springbootmybatis.Test;

import java.math.BigDecimal;

/**
 * @ClassName:MTest
 * @Author:QinJinxiang
 * @Date:2018/6/27 17:56
 * @Description:TODO
 **/
public class MTest {
    public static void main(String[] args) {
        System.out.println("---------------");

        ROUND_UP();
        System.out.println("---------------");

        ROUND_DOWN();
        System.out.println("---------------");


        ROUND_CEILING();
        System.out.println("---------------");


        ROUND_FLOOR();
        System.out.println("---------------");


        ROUND_HALF_UP();
        System.out.println("---------------");


        ROUND_HALF_DOWN();
        System.out.println("---------------");


        ROUND_HALF_EVEN();
        System.out.println("---------------");


        ROUND_UNNECESSARY();
        System.out.println("---------------");


    }

    private static void ROUND_UP(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_UP);
        System.out.println("ROUND_UP -12.4444 = "+f);

    }

    private static void ROUND_DOWN(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_DOWN);
        System.out.println("ROUND_DOWN -12.4444 = "+f);
    }

    private static void ROUND_CEILING(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_CEILING);
        System.out.println("ROUND_CEILING -12.4444 = "+f);
    }

    private static void ROUND_FLOOR(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_FLOOR);
        System.out.println("ROUND_FLOOR -12.4444 = "+f);
    }

    private static void ROUND_HALF_UP(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_HALF_UP);
        System.out.println("ROUND_HALF_UP -12.4444 = "+f);
    }

    private static void ROUND_HALF_DOWN(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_HALF_DOWN);
        System.out.println("ROUND_HALF_DOWN -12.4444 = "+f);
    }

    private static void ROUND_HALF_EVEN(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_HALF_EVEN);
        System.out.println("ROUND_HALF_EVEN -12.4444 = "+f);
    }

    private static void ROUND_UNNECESSARY(){
        BigDecimal a =new BigDecimal(String.valueOf(12.5555)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY 12.5555 = "+a);

        BigDecimal b =new BigDecimal(String.valueOf(12.6666)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY 12.6666 = "+b);

        BigDecimal c =new BigDecimal(String.valueOf(12.4444)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY 12.4444 = "+c);

        BigDecimal d =new BigDecimal(String.valueOf(-12.5555)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY -12.5555 = "+d);

        BigDecimal e =new BigDecimal(String.valueOf(-12.6666)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY -12.6666 = "+e);

        BigDecimal f =new BigDecimal(String.valueOf(-12.4444)).setScale(2,BigDecimal.ROUND_UNNECESSARY);
        System.out.println("ROUND_UNNECESSARY -12.4444 = "+f);
    }
    
}
运行结果： ---------------
ROUND_UP 12.5555 = 12.56
ROUND_UP 12.6666 = 12.67
ROUND_UP 12.4444 = 12.45
ROUND_UP -12.5555 = -12.56
ROUND_UP -12.6666 = -12.67
ROUND_UP -12.4444 = -12.45
---------------
ROUND_DOWN 12.5555 = 12.55
ROUND_DOWN 12.6666 = 12.66
ROUND_DOWN 12.4444 = 12.44
ROUND_DOWN -12.5555 = -12.55
ROUND_DOWN -12.6666 = -12.66
ROUND_DOWN -12.4444 = -12.44
---------------
ROUND_CEILING 12.5555 = 12.56
ROUND_CEILING 12.6666 = 12.67
ROUND_CEILING 12.4444 = 12.45
ROUND_CEILING -12.5555 = -12.55
ROUND_CEILING -12.6666 = -12.66
ROUND_CEILING -12.4444 = -12.44
---------------
ROUND_FLOOR 12.5555 = 12.55
ROUND_FLOOR 12.6666 = 12.66
ROUND_FLOOR 12.4444 = 12.44
ROUND_FLOOR -12.5555 = -12.56
ROUND_FLOOR -12.6666 = -12.67
ROUND_FLOOR -12.4444 = -12.45
---------------
ROUND_HALF_UP 12.5555 = 12.56
ROUND_HALF_UP 12.6666 = 12.67
ROUND_HALF_UP 12.4444 = 12.44
ROUND_HALF_UP -12.5555 = -12.56
ROUND_HALF_UP -12.6666 = -12.67
ROUND_HALF_UP -12.4444 = -12.44
---------------
ROUND_HALF_DOWN 12.5555 = 12.56
ROUND_HALF_DOWN 12.6666 = 12.67
ROUND_HALF_DOWN 12.4444 = 12.44
ROUND_HALF_DOWN -12.5555 = -12.56
ROUND_HALF_DOWN -12.6666 = -12.67
ROUND_HALF_DOWN -12.4444 = -12.44
---------------
ROUND_HALF_EVEN 12.5555 = 12.56
ROUND_HALF_EVEN 12.6666 = 12.67
ROUND_HALF_EVEN 12.4444 = 12.44
ROUND_HALF_EVEN -12.5555 = -12.56
ROUND_HALF_EVEN -12.6666 = -12.67
ROUND_HALF_EVEN -12.4444 = -12.44
---------------

 

 

在银行、账户、计费等领域，BigDecimal提供了精确的数值计算。其中8种舍入方式值得掌握。java

一、ROUND_UPspring

舍入远离零的舍入模式。springboot

在丢弃非零部分以前始终增长数字(始终对非零舍弃部分前面的数字加1)。mybatis

注意，此舍入模式始终不会减小计算值的大小。post

二、ROUND_DOWNspa

接近零的舍入模式。code

在丢弃某部分以前始终不增长数字(从不对舍弃部分前面的数字加1，即截短)。blog

注意，此舍入模式始终不会增长计算值的大小。ip

三、ROUND_CEILINGci

接近正无穷大的舍入模式。

若是 BigDecimal 为正，则舍入行为与 ROUND_UP 相同;

若是为负，则舍入行为与 ROUND_DOWN 相同。

注意，此舍入模式始终不会减小计算值。

四、ROUND_FLOOR

接近负无穷大的舍入模式。

若是 BigDecimal 为正，则舍入行为与 ROUND_DOWN 相同;

若是为负，则舍入行为与 ROUND_UP 相同。

注意，此舍入模式始终不会增长计算值。

五、ROUND_HALF_UP

向“最接近的”数字舍入，若是与两个相邻数字的距离相等，则为向上舍入的舍入模式。

若是舍弃部分 >= 0.5，则舍入行为与 ROUND_UP 相同;不然舍入行为与 ROUND_DOWN 相同。

注意，这是咱们大多数人在小学时就学过的舍入模式(四舍五入)。

六、ROUND_HALF_DOWN

向“最接近的”数字舍入，若是与两个相邻数字的距离相等，则为上舍入的舍入模式。

若是舍弃部分 > 0.5，则舍入行为与 ROUND_UP 相同;不然舍入行为与 ROUND_DOWN 相同(五舍六入)。

七、ROUND_HALF_EVEN    银行家舍入法

向“最接近的”数字舍入，若是与两个相邻数字的距离相等，则向相邻的偶数舍入。

若是舍弃部分左边的数字为奇数，则舍入行为与 ROUND_HALF_UP 相同;

若是为偶数，则舍入行为与 ROUND_HALF_DOWN 相同。

注意，在重复进行一系列计算时，此舍入模式能够将累加错误减到最小。

此舍入模式也称为“银行家舍入法”，主要在美国使用。四舍六入，五分两种状况。

若是前一位为奇数，则入位，不然舍去。

如下例子为保留小数点1位，那么这种舍入方式下的结果。

1.15>1.2 1.25>1.2

八、ROUND_UNNECESSARY

断言请求的操做具备精确的结果，所以不须要舍入。

若是对得到精确结果的操做指定此舍入模式，则抛出ArithmeticException。

 经常使用取值四舍五入（ROUND_HALF_UP） ；

由于咱们是属于互联网金融行业，全部在进行计算的时候尽可能使用ROUND_HALF_EVEN    银行家舍入法

相关文章
相关标签/搜索
每日一句
    每一个你不满意的现在，都有一个你没有努力的曾经。
本站公众号
   欢迎关注本站公众号,获取更多信息
联系我们 最近搜索 最新文章 沪ICP备13005482号-10 MyBatis教程 SQL 教程 MySQL教程 Java 教程 Thymeleaf 教程 Hibernate教程 Spring教程 Redis教程