BigDecimal movePointRight和scaleByPowerOfTen有什么区别？ [英] What is the difference between BigDecimal movePointRight and scaleByPowerOfTen?

问题描述

使用以下代码：

BigDecimal x = new BigDecimal("34.5678");
BigDecimal a = x.movePointRight(3);
BigDecimal b = x.scaleByPowerOfTen(3);
BigDecimal c = x.movePointRight(-3);
BigDecimal d = x.scaleByPowerOfTen(-3);

a和b均为34567.8，c和d均为0.0345678。
a.scale（）和 b.scale 均为1且 c .scale（）和 d.scale（）都是7。

a and b are both 34567.8 and c and d are both 0.0345678. a.scale() and b.scale are both 1 and c.scale() and d.scale() are both 7.

In这两种方法在什么情况下产生不同的结果？

In what circumstances do these two methods produce different results?

推荐答案

• movePointRight 将防止出现负面比例，如果它导致一个。


• scaleByPowerOfTen 不会阻止此。


• movePointRight will prevent a negative scale from occurring if it results in one.
• scaleByPowerOfTen will not prevent this.

示例代码：

import java.math.BigDecimal;

public class BigDecimalScale {
  public static void main(String... args) {
    long base = 12345;
    int scale = 4;

    BigDecimal number = BigDecimal.valueOf(base, scale);
    System.out.println(number);
    BigDecimal pointRight = number.movePointRight(5);
    System.out.println(pointRight + "; my scale is " + pointRight.scale());
    BigDecimal scaleBy = number.scaleByPowerOfTen(5);
    System.out.println(scaleBy + "; my scale is " + scaleBy.scale());
  }
}

结果：

1.2345
123450; my scale is 0
1.2345E+5; my scale is -1

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