I'm building some regex expressions to match naming conventions in Sigasi Studio (which uses Java syntax for regex). For example, a port name must end in _i or _o - e.g. my_input_port_i
I tried using the txt2re generator, however instead of a simple expression it generated code.
Looking at regex syntax, it seems that the "$" character (end of line) and the "|" symbol (OR) could be helpful - something like $_i|_o but after testing with regex101.com no matches are found.
Naming convention dialog:
In Sigasi Studio the entire name should match. So your are looking for:
.*_[io]
The $ means end of the string, but you use it at the beginning.
Maybe you are looking for this at the end of the string, which uses an underscore _, then a character class to match i or o and then matches the end of the string $
_[io]$
Related
Need to allow user to enter only Numbers or alphabets or spaces or hyphens OR combination of any of the above.
and i tried the following
String regex = "/^[0-9A-Za-z\s\-]+$/";
sampleString.matches(regex);
but it is not working properly. would somebody help me to fix please.
Issue : your regex is trying to match / symbol at the beginning and at the end
In java there is no need of / before and after regex so use, java!=javascript
"^[0-9A-Za-z\\s-]+$"
^[0-9A-Za-z\\s-]+$ : ^ beginning of match
[0-9A-Za-z\\s-]+ : one or more alphabets, numbers , spaces and -
$ : end of match
You are close but need to make two changes.
The first is to double-escape (i.e., use \\ instead of \). This is due to the weirdness of Java (see the section "Backslashes, escapes, and quoting" in Javadoc for the Pattern class). The second thing is to drop the explicit reference to the start and end of the string. That's going to be implied when using matches(). So the correct Java code is
String regex = "[0-9A-Za-z\\s\\-]+";
sampleString.matches(regex);
While that will work, you can also replace the "0-9" reference with \d and drop the escaping of the "-". That gives you
String regex = "[\\dA-Za-z\\s-]+";
I work on a product that provides a Java API to extend it.
The API provides a function which
takes a Perl regular expression and
returns a list of matching files.
I want to filter the list to remove all files that end in .xml, .xsl and .cfg; basically the opposite of .*(\.xml|\.xsl|\.cfg).
I have been searching but I haven't been able to get anything to work yet.
I tried .*(?!\.cfg) and ^((?!cfg).)*$ and \.(?!cfg$|?!xml$|?!xsl$).
I don't know if I am on the right track or not.
Note
I know the regex systems are similar, but I can't get a Java regex working either.
You may use
^(?!.*\.(x[ms]l|cfg)$).+
See the regex demo
Details:
^ - start of a string
(?!.*\.(x[ms]l|cfg)$) - a negative lookahead that fails the match if any 0+ chars other than line break chars (.*) are followed with xml, xsl or cfg ((x[ms]l|cfg)) at the end of the string ($)
.+ - any 1 or more chars other than linebreak chars. Might be omitted if the entire string match is not required (in some tools it is required though).
You need something like this, which matches only if the end of the string isn't preceded by a dot and one of the three unwanted types
/(?<!\.(?:xml|xsl|cfg))\z/
I am trying to modify an existing Regex expression being pulled in from a properties file from a Java program that someone else built.
The current Regex expression used to match an email address is -
RR.emailRegex=^[a-zA-Z0-9_\\.]+#[a-zA-Z0-9_]+\\.[a-zA-Z0-9_]+$
That matches email addresses such as abc.xyz#example.com, but now some email addresses have dashes in them such as abc-def.xyz#example.com and those are failing the Regex pattern match.
What would my new Regex expression be to add the dash to that regular expression match or is there a better way to represent that?
Basing on the regex you are using, you can add the dash into your character class:
RR.emailRegex=^[a-zA-Z0-9_\\.]+#[a-zA-Z0-9_]+\\.[a-zA-Z0-9_]+$
add
RR.emailRegex=^[a-zA-Z0-9_\\.-]+#[a-zA-Z0-9_-]+\\.[a-zA-Z0-9_-]+$
Btw, you can shorten your regex like this:
RR.emailRegex=^[\\w.-]+#[\\w-]+\\.[\\w-]+$
Anyway, I would use Apache EmailValidator instead like this:
if (EmailValidator.getInstance().isValid(email)) ....
Meaning of - inside a character class is different than used elsewhere. Inside character class - denotes range. e.g. 0-9. If you want to include -, write it in beginning or ending of character class like [-0-9] or [0-9-].
You also don't need to escape . inside character class because it is treated as . literally inside character class.
Your regex can be simplified further. \w denotes [A-Za-z0-9_]. So you can use
^[-\w.]+#[\w]+\.[\w]+$
In Java, this can be written as
^[-\\w.]+#[\\w]+\\.[\\w]+$
^[a-zA-Z0-9_\\.\\-]+#[a-zA-Z0-9_]+\\.[a-zA-Z0-9_]+$
Should solve your problem. In regex you need to escape anything that has meaning in the Regex engine (eg. -, ?, *, etc.).
The correct Regex fix is below.
OLD Regex Expression
^[a-zA-Z0-9_\\.]+#[a-zA-Z0-9_]+\\.[a-zA-Z0-9_]+$
NEW Regex Expression
^[a-zA-Z0-9_.+-]+#[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$
Actually I read this post it covers all special cases, so the best one that's work correctly with java is
String pattern ="(?:[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")#(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?|\\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-zA-Z0-9-]*[a-zA-Z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";
when I tried this regex
\"(\S\S+)\"(?!;c)
on this string "MM:";d it comes as matched as I wanted
and on this string "MM:";c it comes as not matched as desired.
But when I add a second group, by moving the semicolon inside that group and making it optional using |
\"(\S\S+)\"(;|)(?!c)
for this string "MM:";c it comes as matched when I expected it to not like before.
I tried this on Java and then on Javascript using Regex tool debuggex:
This link contains a snippet of the above
What am I doing wrong?
note the | is so it is not necessary to have a semicolon.Also in the examples I put c, it is just a substitute in the example for a word, that's why I am using negative lookahead.
After following Holgers response of using Possessive Quantifiers,
\"(\S\S+)\";?+(?!c)
it worked, here is a link to it on RegexPlanet
I believe that the regex will do what it can to find a match; since your expression said the semicolon could be optional, it found that it could match the entire expression (since if the semicolon is not consumed by the first group, it becomes a "no-match" for the negative lookahead. This has to do with the recursive way that regex works: it keeps trying to find a match...
In other words, the process goes like this:
MM:" - matched
(;|) - try semicolon? matched
(?!c) - oops - negative lookahead fails. No match. Go back
(;|) - try nothing. We still have ';c' left to match
(?!c) - negative lookahead not matched. We have a match
An update (based on your comment). The following code may work better:
\"(\S\S+)\"(;|)((?!c)|(?!;c))
Debuggex Demo
The problem is that you don’t want to make the semicolon optional in the sense of regular expression. An optional semicolon implies that the matcher is allowed to try both, matching with or without it. So even if the semicolon is there the matcher can ignore it creating an empty match for the group letting the lookahead succeed.
But you want to consume the semicolon if it’s there, so it is not allowed to be used to satisfy the negative look-ahead. With Java’s regex engine that’s pretty easy: use ;?+
This is called a “possessive quantifier”. Like with the ? the semicolon doesn’t need to be there but if it’s there it must match and cannot be ignored. So the regex engine has no alternatives any more.
So the entire pattern looks like \"(\S\S+)\";?+(?!c) or \"(\S\S+)\"(;?+)(?!c) if you need the semicolon in a group.
I have searched everywhere and I cannot find what I am doing wrong.
I have this regular expression: ^(\[\[).+(\]\]) that I want to match for this data that starts just at the beginning of the line as shown below (I do not want to match anything but the things starting at the beginning of a line):
[[match this]] [[don't match this]]
{{Link GA|es}}
{{Link FA|ca}}
And for some reason it is not matching anything in Java (or other regex "testers" such as regexpal.com). By "in Java" i mean with the String.replaceAll(String regex, String replacement) method in the Java String API.
But, if I omit the ^ and just have (\[\[).+(\]\]) it matches fine at the beginning of the line, but also matches inline instances which I do not want.
Can anyone point out what the error is here? Thank you
^ means "start of string", not "start of line", unless you use the Pattern.MULTILINE (or (?m)) option when building the regex. Also, you should be using a lazy quantifier (as pointed out by Dave Newton in his comment).
Finally, don't forget to double the backslashes:
String result = subject.replaceAll("(?m)^\\[\\[.+?\\]\\]", "");
.+ is greedy, in that it will match everything it can (here, matching everything up to the last \]\]
To stop this behaviour just add a ? to make it non-greedy
^\[\[.+?\]\]
Will match [[ then look for any characters until it finds the first occurrence of ]]
(\[\[).+(\]\]){1}+ {1}+ that mean exactly one time's improve link