Java 检查双精度值是否大于零的简单方法
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Simple way to check if double value is greater than zero
提问by Pirate_Hyman
I have a double variable(employeeSalary) and I want to check if this value is greater than(>) zero(0). I can think of very naive way to write this code but I am not sure if for doubledata type this is correct way to write.
我有一个双变量（employeeSalary），我想检查这个值是否大于（>）零（0）。我可以想到编写此代码的非常幼稚的方法，但我不确定对于双数据类型这是否是正确的编写方式。
if(employeeSalary > 0){
// Employee salary is greater than zero.
}else{
// Employee salary is less than or equal to zero.
}
Can anyone please tell me if this approach works?
谁能告诉我这种方法是否有效？
回答by OldCurmudgeon
There are danger areas when comparing doublevalues but using >or <is not a problem. Your code should work perfectly.
比较double值时存在危险区域，但使用>or<不是问题。您的代码应该可以完美运行。
You should, however, be wary of using ==as there are many edge cases where a number that seems to be 0is not (e.g. -0.0) and a number is effectively zero (e.g. 0.0000...001) but comparing with == 0will fail.
但是，您应该小心使用==，因为在许多边缘情况下，似乎0不是的数字（例如-0.0）和数字实际上为零（例如0.0000...001）但与 比较== 0将失败。
回答by Michael Peacock
If you're just wanting to compare primitives, you can certainly do something like:
如果您只是想比较原语，您当然可以执行以下操作：
if(employeeSalary > 0.0){
// Employee salary is greater than zero.
}else{
// Employee salary is less than or equal to zero.
}
Note that, if employeeSalary is a double (primitive) then you should really compare this to other double rather than an int.
请注意，如果employeeSalary 是double（原始），那么您应该真正将其与其他double 而不是int 进行比较。
You could also use a couple Double static methods to do the same
你也可以使用几个 Double 静态方法来做同样的事情
// assuming employeeSalary is a double
if(Double.compare(employeeSalary, Double.valueOf(0.0)) > 0 ){
// Employee salary is greater than zero.
}else{
// Employee salary is less than or equal to zero.
}
See: https://docs.oracle.com/javase/7/docs/api/java/lang/Double.html#compare(double,%20double)
请参阅：https: //docs.oracle.com/javase/7/docs/api/java/lang/Double.html#compare(double,%20double)
