[英]regular expression that starts with an underscore but not contains any underscore
I am trying to fetch the name of a file without the part from the last underscore until the end. 我试图从最后一个下划线获取文件的名称,直到结束。
For example, ABC_AA.xml
should be ABC
and ABC_AASD_AD_AA.xml
should be ABC_AASD_AD
例如,
ABC_AA.xml
应为ABC
, ABC_AASD_AD_AA.xml
应为ABC_AASD_AD
I am thinking about using non-greedy with exlusive ^
symbol. 我正在考虑使用非贪婪的exlusive
^
符号。 I have tried this: 我试过这个:
String nameToSearch = testName.replaceAll("_(^(_).)+\\.xml$", "");
How about using simple substring instead of regex 如何使用简单的子串而不是正则表达式
String nameToSearch = testName.substring(0, testName.lastIndexOf('_'));
or in case there can be no _
you can use 或者如果没有
_
你可以使用
String noSuffix = testName.substring(0, testName.lastIndexOf('.'));//remove ".xml"
String nameToSearch = noSuffix.substring(0, testName.lastIndexOf('_'));
But if you really want to use regex then you can try with 但如果你真的想使用正则表达式,那么你可以试试
testName.replaceAll("_[^_]*[.]xml$", "");
which will match (and remove) _
which has zero or more non _
characters [^_]*
and ends with .xml
. 它将匹配(并删除)
_
具有零个或多个非_
字符[^_]*
并以.xml
结尾。
In case there can be no _
you can make _[^_]*
optional with 如果没有
_
你可以使用_[^_]*
可选
testName.replaceAll("(_[^_]*)?[.]xml$", "");
Simple. 简单。
Use groups and back-references, as such: 使用组和反向引用,如下所示:
String input = "ABC_AASD_AD_AA.xml";
// | using replaceAll to pass regex
// | | group 1: one or more characters, greedy
// | | | underscore
// | | || one or more characters, reluctant
// | | || | escaped dot and extension
// | | || | | back-reference to group 1
System.out.println(input.replaceAll("(.+)_.+?\\.xml", "$1"));
Output 产量
ABC_AASD_AD
Note 注意
Any input not conforming to the Pattern
will be returned as such. 任何不符合
Pattern
输入都将被退回。
我相信这个正则表达式应该有效:
String repl = str.replaceFirst("_[^_]+$", "");
The ^
character can be used as "exclusive", ie to exclude certain characters, only as the first character of a character class inside []
. ^
字符可以用作“独占”,即排除某些字符, 仅作为[]
内字符类的第一个字符。 [^_]
matches any character that's not an underscore. [^_]
匹配任何不是下划线的字符。 Outside of square brackets, it means "the beginning of the source string". 在方括号之外,它表示“源字符串的开头”。
So you're close. 所以你很亲密。 Try this:
尝试这个:
String nameToSearch = testName.replaceAll("_[^_]+\\.xml$", "");
Or, if you want to handle file names ending in underscore (ie change ABC_.XML
to ABC
), and remove the underscore in that case, change +
(1 or more) to *
(0 or more). 或者,如果要处理以下划线结尾的文件名(
ABC_.XML
更改为ABC
),并在该情况下删除下划线,请将+
(1或更多)更改为*
(0或更多)。
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