I'm trying to create a reg expression to find a sequence of the char 'y' and a '/' before or after it. But only if nothing is after or before the '/' characters. This is better explained with examples. Basically, I need to remove these from the String.
For example:
'dd/MM/yyyy' becomes 'dd/MM'
'dd/yy/MM' becomes 'dd/MM'
'y/MM/dd' becomes 'MM/dd'
Is this even possible with Regex? And if it isn't, what's the best way to approach this? Just if-then logic?
You can use
String replacement = inputString.replaceAll("/y+|y+/","");
What about replacing: \/y+|y+\/ with nothing?
Related
What I want is a class code like ACCT 4838.
I tried
String REGEX = "[a-zA-Z][a-zA-Z][a-zA-Z][a-zA-Z][\\s][\\d][\\d][\\d][\\d]";
String REGEX = "[a-zA-Z][a-zA-Z][a-zA-Z][a-zA-Z]\\s\\d\\d\\d\\d"
I apologize if this gets flagged i have been looking around for a while and i cant quite peg what it is im doing wrong. should be a quick one for someone.
You can use a regex like this:
(?i)^[a-z]{4} \d{4}$ // With inline insensitive flag
^[A-Za-z]{4} \d{4}$ // without inline flag
Remember to escape backslashes in java like ^[A-Za-z]{4} \\d{4}$
IdeOne example
Below works. In java the single \ gives an error. I was stupidly feeding in the wrong string in addition to not having the proper code.
String REGEX = "^[a-zA-Z][a-zA-Z][a-zA-Z][a-zA-Z]\s\d\d\d\d";
is it possible to detect the pattern of a String and store it in a variable? so, if I have a String test1234 and highlight 1234 I expect something like \d{4}.
It would require that you find a regular expression that both your highlighted substring and desired replacement match and that is in no way unique. For example, "1234" could match .{4} or \d{4} or even .+ , which is not of a unique length. So, even if you could generate a regular expression from a string, it could happen that it would be the string itself or something you didn't want. Maybe you should rethink the general desired outcome of your program and try to come up with a different way of solving the issue at hand.
Hope that helped. Good luck!
To validate String in Java I can use String.matches(). I would like to validate a simple string "*.txt" where "*" means anything. Input e.g. test.txt is correct, but test.tt is not correct, because of ".tt". I tried to use matches("[*].txt"), but it doesn't work. How can I improve this matches? Thanks.
Do not use code, you don't understand!
For your simple problem you could totally avoid using a regular expression and just use
yourString.endsWith(".txt")
and if you want to perform this comparison case insensitive (i.e. allow ".TXT" or ".tXt") use
yourString.toLowerCase().endsWith(".txt")
If you want to learn more about regular expressions in java, I'd recomment a tutorial. For example this one.
You may try this for txt files:
"file.txt".matches("^.*[.]txt$")
Basically ^ means the start of your string. .* means match anything greedy, hence as much as you can get to make the expression match. And [.] means match the dot character. The suffix txt is just the txt text itself. And finally $ is the anchor for the end of the string, which ensures that the string does not contain anything more.
Use .+, it means any character having one or unlimited lengths. It will ensure to avoid the inputs like only .txt
matches(".+[.]txt")
FYI: [.] simply matches with the dot character.
what is the regular expression which i should use to match a string which starts with SDPCDR
and contains date in the format 20120826 and ends with .asn ?
an example string is SDPCDR_delsdp3a_6091_20120826-042451.asn
This would work:
^SDPCDR\w+(\d{8})-\w+.asn$
"^SDPCDR.*\\d{8}.*\\.asn$"
Pretty generous on the date part, but the string is probably specific enough already to avoid false matches. If you're looking for a substring rather than trying to match the entire string, instead use
"SDPCDR.*?\\d{8}.*?\\.asn"
SDPCR_[a-z_]*[0-9]{8,8}-[a-z_]*\\\\.asn
I have this java string:
String bla = "<my:string>invalid_content</my:string>";
How can I replace the "invalid_content" piece?
I know I should use something like this:
bla.replaceAll(regex,"new_content");
in order to have:
"<my:string>new_content</my:string>";
but I can't discover how to create the correct regex
help please :)
You could do something like
String ResultString = subjectString.replaceAll("(<my:string>)(.*)(</my:string>)", "$1whatever$3");
Mark's answer will work, but can be improved with two simple changes:
The central parentheses are redundant if you're not using that group.
Making it non-greedy will help if you have multiple my:string tags to match.
Giving:
String ResultString = SubjectString.replaceAll
( "(<my:string>).*?(</my:string>)" , "$1whatever$2" );
But that's still not how I'd write it - the replacement can be simplified using lookbehind and lookahead, and you can avoid repeating the tag name, like this:
String ResultString = SubjectString.replaceAll
( "(?<=<(my:string)>).*?(?=</\1>)" , "whatever" );
Of course, this latter one may not be as friendly to those who don't yet know regex - it is however more maintainable/flexible, so worth using if you might need to match more than just my:string tags.
See Java regex tutorial and check out character classes and capturing groups.
The PCRE would be:
/invalid_content/
For a simple substitution. What more do you want?
Is invalid_content a fix value? If so you could simply replace that with your new content using:
bla = bla.replaceAll("invalid_content","new_content");