BigDecimal乘以100的几种方法及性能测试

桃扇骨 2022-08-30 14:55 223阅读 0赞

最近用到decimal计算要乘100

//修改主观题得分率为：主观题得分/总分   修改客观题得分率为：客观题得分/总分
    if (Objects.nonNull(exam.getTotalScore()) && exam.getTotalScore().compareTo(BigDecimal.ZERO) != 0) {
        userExamReviewList.setSubjectiveScoreRate(userExamReviewDTO.getSubjectiveScore().multiply(new BigDecimal(100)).divide(exam.getTotalScore(), 2, ROUND_HALF_UP).floatValue());
        userExamReviewList.setCorrectRate(userExamReviewDTO.getObjectiveScore().multiply(new BigDecimal(100)).divide(exam.getTotalScore(), 2, ROUND_HALF_UP).floatValue());
    }

有没有优雅一点的处理方式呢？以及他们的性能怎么样？

import java.math.BigDecimal;
    
    /**
     * @Title: BigDecimal乘以100的几种方法 及性能测试
     * @Author: ken
     * @Description:
     * @Date: 2021/7/21  9:32
     * @Param:
     * @return
     **/
    public class TestDecimal {
        public static void main(String[] args) {
            BigDecimal b1 = new BigDecimal(0);
            //movePointRight
            long start = System.currentTimeMillis();
            for(int i = 0; i <10000000; i ++){
                BigDecimal d = new BigDecimal(99);
                b1 = d.movePointRight(2);
    /*            if(i >90 && i<= 100){
                    System.out.println(b1);
                }*/
            }
            long end = System.currentTimeMillis();
            System.out.println("movePointRight:" + (end -start) );
            //multiply
            start = System.currentTimeMillis();
            for(int i = 0; i <10000000; i ++){
                BigDecimal d = new BigDecimal(99);
                b1 = d.multiply(BigDecimal.TEN).multiply(BigDecimal.TEN);
    /*            if(i >90 && i<= 100){
                    System.out.println(b1);
                }*/
            }
            end = System.currentTimeMillis();
            System.out.println("multiply:" + (end -start) );
            //scaleByPowerOfTen
            start = System.currentTimeMillis();
            for(int i = 0; i <10000000; i ++){
                BigDecimal d = new BigDecimal(99);
                b1 = d.scaleByPowerOfTen(2);
                b1.toPlainString();
                /*if(i >90 && i<= 100){
                    System.out.println(b1);
                    System.out.println(b1.toPlainString());
                }*/
            }
            end = System.currentTimeMillis();
            System.out.println("scaleByPowerOfTen:" + (end -start) );
    
        }
    }

看看他们的性能：

"C:\Program Files\Java\jdk1.8.0_231\bin\java.exe" "-javaagent:E:\program files\JetBrains\IntelliJ IDEA 2019.1.3\lib\idea_rt.jar=58898:E:\program files\JetBrains\IntelliJ IDEA 2019.1.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_231\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_231\jre\lib\rt.jar;E:\NewWorld\work\workspace\classes\production\QianQian" TestDecimalmovePointRight:21multiply:38scaleByPowerOfTen:5

scaleByPowerOfTen > movePointRight > multiply

scaleByPowerOfTen 性能最佳，但是输出的是 科学计算法：9.9E+3

使用 toPlainString（）可以原样输出：

//输出 9900

System.out.println(b1.toPlainString());

但是这样处理后性能不及 movePointRight

movePointRight > multiply > scaleByPowerOfTen

![图片][39927c2d50437d334dc058ba9a6edd9d.png]

[39927c2d50437d334dc058ba9a6edd9d.png]: /images/20220829/c9133e8359e6405baa8013888f2febfc.png