(可能有点奇怪)长增量行为？

Question

在提出这个问题时我有点尴尬,但以下代码片段的结果让我难过:

System.out.println("incrementResultResponses() has been invoked!");
final long oldValue = resultResponses;
final long newValue = resultResponses++;
System.out.println("Old value = " + oldValue);
System.out.println("New value = " + newValue);

这输出如下:

incrementResultResponses() has been invoked!
Old value = 0
New value = 0

为什么？并发会对结果有什么影响吗？顺便说一下,resultResponses是一个long.

Answer 1

后缀++运算符返回旧值(在递增之前).你想使用前缀++:

final long oldValue = resultResponses;
final long newValue = ++resultResponses;