BigDecimal movePointRight和scaleByPowerOfTen有什么区别？

Question

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()并且b.scale都是1 c.scale()和d.scale()都是7.

这两种方法在什么情况下产生不同的结果？

Answer 1

• movePointRight 如果导致一个负面规模,将防止发生负面规模.
• scaleByPowerOfTen 不会阻止这一点.

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