Java逻辑符号 [英] Notation for logic in Java

问题描述

我在Google上很难找到一个绝对基本的Java问题.以下是什么意思:

Absolutely basic Java question which I'm having a hard time finding on Google. What does the following mean:

(7 & 8) == 0?

那等同于写作:

7 == 0 || 8 == 0?

我写了一个快速主干来测试这一点，事实似乎是这样.我只是想确保自己没有遗漏任何东西.

I wrote a quick main which tests this, and it seems to be the case. I just wanted to make sure I'm not missing anything.

推荐答案

不是. &是按位和.如果在两个输入中都设置了相应的位，则它将设置一个位.由于在二进制中，7是111，8是1000，因此它们没有共同的位，因此结果是0.

Nope. & is bitwise and. It sets a bit if the corresponding bits are set in both inputs. Since in binary, 7 is 111 and 8 is 1000, they have no bits in common, so the result is 0.

对于您建议的内容，实际上并没有任何速记语法，只能一行显示.有几种解决方法-测试Set或BitSet中的成员资格，使用switch语句-但没有什么比7 == 0 || 8 == 0既高效又短.

There isn't really any shorthand syntax for the thing you suggest, not on a single line. There are a few workarounds -- test for membership in a Set or BitSet, use a switch statement -- but nothing that's both as efficient and as short as just 7 == 0 || 8 == 0.

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