正则表达式没有双值[重复]

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Double toString or String.valufOf not returning right value [duplicate] 1 answer
Double toString或String.valufOf没有返回正确的值[复制] 1个答案

Double dbl = 0.003;
String str = dbl.toString();

str.matches("^\\d{1,7}\\.?\\d{1,3}$");

regex returns false.

正则表达式返回false。

str value returns as 0.0030

str值返回0.0030

Regex is failing which is different from Float problem.

正则表达式失败，这与Float问题不同。

2 个解决方案

#1

It is indeed behaving correctly (the regex bit I mean). You've limited the digits to three following the decimal and you're giving it four.

它确实表现正常（我的意思是正则表达式）。你已经将数字限制在小数点后面的三位数，你给它四位数。

I'd suggest either modifying the string to remove trailing zeros (assuming they're after a decimal point of course), or changing the regex to make it suitable.

我建议修改字符串以删除尾随零（假设它们当然是在小数点之后），或者更改正则表达式以使其适合。

The former can be done with something like:

前者可以通过以下方式完成：

s = s.replaceFirst("(\\.\\d+)0+$", "$1").replaceFirst("\\.0+$", ".0");

The latter involves adding zeros to the end of the regex:

后者涉及在正则表达式的末尾添加零：

str.matches("^\\d{1,7}\\.?\\d{1,3}0*$");

You may also want to consider putting the decimal and fractional digits into a group, regardless of which method you choose. In other words, something like:

您可能还需要考虑将小数位和小数位放入一个组中，无论您选择哪种方法。换句话说，类似于：

    str.matches("^\\d{1,7}(\\.\\d{1,3})?$");

As it stands now, that regex will also accept a 10-digit integral number.

就目前而言，正则表达式也将接受10位整数。

#2

As I pointed out in your other question, you are just running into the known bug-

正如我在你的另一个问题中指出的那样，你刚刚遇到已知的错误 -

http://bugs.java.com/view_bug.do?bug_id=4428022

0050 is not 3-character long. Hence, false. You can try updating your JDK environment or use printf. In my JDK7, I get-

0050不是3个字符长。因此，错误。您可以尝试更新JDK环境或使用printf。在我的JDK7中，我得到 -

0.005

0.005

true

真正

#1