将BigDecimal乘以100哪种方法更好? [英] Which method will be better when multiply 100 with BigDecimal?

问题描述

在这里，当我使用Java BigDecimal时遇到一个问题. 当我想将100乘以BigDecimal的对象时，哪种方法会更好.

Here I have a question when using Java BigDecimal. Which way will be better when I want to multiply 100 for a object of BigDecimal.

1. 乘以10两次；
2. movePointRight(2);
3. scaleByPowerOfTen(2);
4. 还有其他方法吗?请告诉我是否有.

顺便说一句，它将用于商业计算，因此我考虑的是精度而不是速度.

BTW, it will be used for commercial calculation, so I'm considering the precision rather than the speed.

推荐答案

选项3最快.选项1和2大致相同(选项一乘以十两次).相反，乘以100会接近选项3的速度.

Option 3 is the fastest. Options 1 and 2 are roughly the same (option one being to multiply by ten twice). Multiplying by 100 instead gets up near the speed of option 3.

这是我的测试代码:

import java.math.BigDecimal;

public class TestingStuff {

    public static void main(String[] args){
        BigDecimal d2 = new BigDecimal(0); // to load the big decimal class outside the loop
        long start = System.currentTimeMillis();
        for(int i = 0; i < 1000000; i++) {
            BigDecimal d = new BigDecimal(99);
            d2 = d.movePointRight(2);
        }
        long end = System.currentTimeMillis();
        System.out.println("movePointRight: " + (end - start));

        BigDecimal ten = new BigDecimal(10);
        start = System.currentTimeMillis();
        for(int i = 0; i < 1000000; i++) {
            BigDecimal d = new BigDecimal(99);
            d2 = d.multiply(ten).multiply(ten);
        }
        end = System.currentTimeMillis();
        System.out.println("multiply: " + (end - start));

        start = System.currentTimeMillis();
        for(int i = 0; i < 1000000; i++) {
            BigDecimal d = new BigDecimal(99);
            d2 = d.scaleByPowerOfTen(2);
        }
        end = System.currentTimeMillis();
        System.out.println("scaleByPowerOfTen: " + (end - start));
    }

}

当然，您可以自己在自己的代码中尝试各种选项.如果您无法衡量差异，那么为什么要进行优化?

Of course you could just try the various options yourself in your own code. If you can't measure the difference, then why are you optimizing?

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