java - Infinity 等于 Java 中的 Infinity

Question

我想测试无穷大是否等于Java中的无穷大:

Double.POSITIVE_INFINITY == Double.POSITIVE_INFINITY

当结果证明是真的时，我感到很惊讶。我的问题是两个无限值如何相等？

Answer 1

因为 Double.POSITIVE_INFINITY 代表一个特定的数字，因此使用 == 将其与自身进行比较应该返回 true。

此行为在 JLS Sec 15.21.1 中明确指定:

Floating-point equality testing is performed in accordance with the rules of the IEEE 754 standard:

• ...

• Otherwise, two distinct floating-point values are considered unequal by the equality operators.

  In particular, there is one value representing positive infinity and one value representing negative infinity; each compares equal only to itself, and each compares unequal to all other values.