java - BigDecimal.ROUND_HALF_UP 和 RoundingMode.HALF_UP 之间的区别？

Question

以下:

new MathContext(precision, RoundingMode.HALF_UP);

似乎有效。但是，以下返回错误:

new MathContext(precision, BigDecimal.ROUND_HALF_UP);

错误:

java: no suitable constructor found for MathContext(int,int)
    constructor java.math.MathContext.MathContext(java.lang.String) is not applicable
      (actual and formal argument lists differ in length)
    constructor java.math.MathContext.MathContext(int,java.math.RoundingMode) is not applicable
      (actual argument int cannot be converted to java.math.RoundingMode by method invocation conversion)
    constructor java.math.MathContext.MathContext(int) is not applicable
      (actual and formal argument lists differ in length)

Answer 1

请注意常量:

RoundingMode.HALF_UP
BigDecimal.ROUND_HALF_UP

根据 Javadocs 和源代码，意思完全相同:

public enum RoundingMode {
....
HALF_UP(BigDecimal.ROUND_HALF_UP),
....
}