和=有什么区别?在Java中?(复制)

This question already has an answer here:

这个问题已经有了答案:

What's this =! operator? [duplicate] 13 answers
这是什么= !运营商吗?(重复)13的答案

I was looking over some mock OCJP questions. I came across a really baffling syntax. Here it is:

我在看一些模拟OCJP问题。我遇到了一个令人困惑的语法。这里是:

class OddStuff {
    public static void main(String[] args) {
        boolean b = false;
        System.out.println((b != b));// False
        System.out.println((b =! b));// True
    }
}

Why does the output change between != and =!?

为什么输出会在!=和=之间变化?

4 个解决方案

#1

110

The question is just playing with you with confusing spacing.

问题是和你玩的时候，空格是混淆的。

b != b is the usual != (not equals) comparison.

b != b是通常的比较。

On the other hand:

另一方面:

b =! b is better written as b = !b which is parsed as:

b = !b最好写成b = !b，解析为:

b = (!b)

Thus it's two operators.

因此,两个操作符。

First invert b.
第一个转化b。
Then assign it back to b.
然后把它分配给b。

The assignment operator returns the assigned value. Therefore, (b =! b) evaluates to true - which is what you print out.

赋值操作符返回赋值。因此,(b = !b)计算结果为真——这是你打印出来的。

#2

b != b means ! (b == b): the opposite of b == b.

b != b的意思!(b = b): b = b的反义词。

b =! b is actually b = !b, an assignment. It's toggling b's value. An assignment evaluates to the value of the expression, so this will evaluate to !b (along with having changed the value of b).

b = !b实际上是b = !这是切换b的值。赋值计算表达式的值，因此它将计算为!b(同时更改了b的值)。

#3

b=!b is an assignment. It assigns b to !b and the expression evaluates to the resulting value, which is true.

b = !b是一个任务。它将b赋给!b，表达式计算得到结果值，这是正确的。

#4

b =! b

b = !b

you are doing an assignment, you are saying that B should have the value of !B.

你在做作业，你是说B应该有B的值。

b != b

b ! = b

You are asking if B is different than b

你问的是B和B是否不同

#1

110