Java 'if' 条件中的布尔检查
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Boolean checking in the 'if' condition
提问by jasonfungsing
Which one is better Java coding style?
哪一种是更好的 Java 编码风格？
boolean status = true;
if (!status) {
//do sth
} else {
//do sth
}
or:
或者：
if (status == false) {
//do sth
} else {
//do sth
}
采纳答案by missingfaktor
Former, of course. Latter is redundant, and only goes to show that you haven't understood the concept of booleans very well.
当然是前者。后者是多余的，只能表明您还没有很好地理解布尔值的概念。
One more suggestion: Choose a different name for your booleanvariable. As per this Java style guide:
还有一个建议：为boolean变量选择一个不同的名称。根据这个 Java 风格指南：
is prefix should be used for boolean variables and methods.
isSet,isVisible,isFinished,isFound,isOpenThis is the naming convention for
booleanmethods and variables used by Sun for the Java core packages.Using the
isprefix solves a common problem of choosing bad boolean names likestatusorflag.isStatusorisFlagsimply doesn't fit, and the programmer is forced to chose more meaningful names.Setter methods for
booleanvariables must have set prefix as in:
void setFound(boolean isFound);There are a few alternatives to the
isprefix that fits better in some situations. These arehas,canandshouldprefixes:boolean hasLicense(); boolean canEvaluate(); boolean shouldAbort = false;
is 前缀应该用于布尔变量和方法。
isSet,isVisible,isFinished,isFound,isOpen这是
booleanSun 为 Java 核心包使用的方法和变量的命名约定 。使用
is前缀解决了选择错误布尔名称（如statusor ）的常见问题flag。isStatus或者isFlag根本不适合，程序员被迫选择更有意义的名称。
boolean变量的Setter 方法必须设置前缀，如下所示：
void setFound(boolean isFound);
is在某些情况下，前缀有一些替代方案 更适合。这些是has,can和should前缀：boolean hasLicense(); boolean canEvaluate(); boolean shouldAbort = false;
回答by user207421
The former. The latter merely adds verbosity.
前者。后者只是增加了冗长。
回答by Singleton
This is more readable and good practice too.
这也更具可读性和良好的实践。
if(!status){
//do sth
}else{
//do sth
}
回答by lijie
The first one, or if (status) { /*second clause*/ } else { /* first clause */ }
第一个，或 if (status) { /*second clause*/ } else { /* first clause */ }
EDIT
编辑
If the second form is really desired, then if (false == status) <etc>, while uglier, is probably safer (wrt typos).
如果确实需要第二种形式，那么if (false == status) <etc>虽然更丑陋，但可能更安全（拼写错误）。
回答by akf
I would suggest that you do:
我建议你这样做：
if (status) {
//positive work
} else {
// negative work
}
The ==tests, while obviously redundant, also run the risk of a single =typo which would result in an assignment.
这些==测试虽然显然是多余的，但也存在=可能导致分配的单一错字的风险。
回答by Nico Huysamen
The first one. But just another point, the following would also make your code more readable:
第一个。但还有一点，以下内容也会使您的代码更具可读性：
if (!status) {
// do false logic
} else {
// do true logic
}
Note that there are extra spaces between ifand the (, and also before the elsestatement.
请注意， 和之间if以及语句(之前有额外的空格else。
EDIT
编辑
As noted by @Mudassir, if there is NOother shared code in the method using the logic, then the better style would be:
正如@Mudassir 所指出的，如果使用该逻辑的方法中没有其他共享代码，那么更好的样式是：
if (!status) {
// do false logic
}
// do true logic
回答by dj_segfault
If you look at the alternatives on this page, of course the first option looks better and the second one is just more verbose. But if you are looking through a large class that someone else wrote, that verbosity can make the difference between realizing right away what the conditional is testing or not.
如果您查看此页面上的替代方案，当然第一个选项看起来更好，而第二个选项更冗长。但是，如果您正在查看其他人编写的大类，那么冗长可能会在立即意识到条件测试与否之间产生差异。
One of the reasons I moved away from Perl is because it relies so heavily on punctuation, which is much slower to interpret while reading.
我放弃 Perl 的原因之一是因为它非常依赖标点符号，在阅读时解释标点符号要慢得多。
I know I'm outvoted here, but I will almost always side with more explicit code so others can read it more accurately. Then again, I would never use a boolean variable called "status" either. Maybe isSuccess or just success, but "status" being true or false does not mean anything to the casual reader intuitively. As you can tell, I'm very into code readability because I read so much code others have written.
我知道我在这里被否决了，但我几乎总是支持更明确的代码，以便其他人可以更准确地阅读它。再说一次，我也永远不会使用名为“status”的布尔变量。也许 isSuccess 或只是成功，但“状态”是真还是假对于不经意的读者凭直觉没有任何意义。如您所知，我非常关注代码可读性，因为我阅读了很多其他人编写的代码。
回答by Petro Semeniuk
First style is better. Though you should use better variable name
第一种风格更好。虽然你应该使用更好的变量名
回答by RAY
It really also depends on how you name your variable.
这实际上还取决于您如何命名变量。
When people are asking "which is better practice" - this implicitly implies that both are correct, so it's just a matter of which is easier to read and maintain.
当人们问“哪个是更好的实践”时 - 这暗示着两者都是正确的，所以这只是一个更容易阅读和维护的问题。
If you name your variable "status" (which is the case in your example code), I would much prefer to see
如果您将变量命名为“状态”（在您的示例代码中就是这种情况），我更希望看到
if(status == false) // if status is false
if(status == false) // if status is false
On the other hand, if you had named your variable isXXX (e.g. isReadableCode), then the former is more readable. consider:
另一方面，如果您将变量命名为 isXXX（例如 isReadableCode），则前者更具可读性。考虑：
if(!isReadable) { // if not readable
System.out.println("I'm having a headache reading your code");
}
回答by asela38
My personal feeling when it comes to reading
个人阅读的感受
if(!status) : if not status
if(status == false) : if status is false
if you are not used to !status reading. I see no harm doing as the second way.
如果您不习惯 !status 阅读。我认为第二种方法没有什么坏处。
if you use "active" instead of status I thing if(!active) is more readable
如果您使用“活动”而不是状态，我认为 if(!active) 更具可读性
