Java - 括号和赋值 [英] Java - parentheses and assignment

问题描述

代码：

int r=1;
System.out.println(r + (r=2));

输出为：3。但我预计4，因为我认为括号内的代码是先执行的？

The output is: 3. But I expected 4 because I thought the code inside the parentheses is executed first?

推荐答案

关于运算符的官方文档说

评估除赋值运算符之外的所有二元运算符从左到右;赋值运算符从右到左进行求值。

All binary operators except for the assignment operators are evaluated from left to right; assignment operators are evaluated right to left.

所以 + 被评估从左到右，其中从右到左评估赋值运算符。

So + is evaluated left-to-right,where as assignment operators are evaluated right to left.

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