Develop Reference

Kotlin regex not working for polish char ("ł") which I get at runtime

I've declared a regex like this:
"(^\\d{1,}\\,\\d{2}|^0) zł$"
Unfortunately it doesn't match below value (but it should)
508,00 zł
NOTE1: I've discovered, that the problem is probably with the ł character
NOTE2: The problem is, that i am getting this String from an API and check it at runtime (it has exact value as I described)
NOTE3: I've also tried to manually match my pattern in the debugger evaluation (when I just typed the "508, 00zł" by hand) and it matched. Unfortunately the string itself that I get doesn't match at runtime. What can be the possible problem?
Code:
val value = getFromApi() // 508,00 zł
val regex = "(^\\d{1,}\\,\\d{2}|^0) zł$".toRegex()
regex.matches(value) // returns false

The letter ł is not a culprit here since there is one Unicode representation for it.
The most common issue is the whitespace: it can be any Unicode whitespace there and from the looks of it, you will never be able to tell.
To match any ASCII whitespace, you may use \s. Here, you had this kind of whitespace, so my top comment below the question worked for you.
To match any Unicode whitespace, you may use \p{Z} to match any one whitespace character, or \p{Z}* to match 0 or more of their occurrences:
val value = "508,00 zł"
val regex = """^(\d+,\d{2}|0)\p{Z}zł$""".toRegex()
// val regex = """^(\d+,\d{2}|0)\p{Z}*zł$""".toRegex()
println(regex.matches(value)) // => True
See Kotlin demo
Also, note the use of the raw string literals (delimited with triple double quotation marks), they enable the use of a single backslash as the regex escape char.
Note {1,} is the same as + quantifier that matches 1 or more repetitions.

Check if www page is in text android

I want to check if www page is in text. For example i have page address: www.taktik.com/trow and want check if text for www is in text.
I use Matcher mW = Pattern.compile("[a-zA-Z0-9_.+-]+.[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+\\/[a-zA-Z0-9-.]+").matcher(question); but I don't get any results. How can I check if text xxx.xxxx.xxx/xxx is in my String?

How can I check if text xxx.xxxx.xxx/xxx is in my String?
Fixing your regex, the pattern may look like
[a-zA-Z0-9_.+-]+\\.[a-zA-Z0-9-]+\\.[a-zA-Z0-9.-]+/[a-zA-Z0-9.-]+
Mind I escaped thr first dot and placed the hyphen at the end of the last two character classes (in yours, you have 9-. that creates a range that matches more than you'd want).
I tried to shorten the pattern a bit, but it's difficult since \w also matches Unicode characters in Android. Here is a possible regex:
(?i)[A-Z0-9_+-]+(?:\\.[A-Z0-9-]+){2}/[A-Z0-9-]+

Create regex pattern for a specified String

I want to check if a String has a specified structure. I think regex would be the best way to test the String, but I have never used regex before and have sadly no clue how it works. I watched some explanations on stackoverflow, but I couldn't find a good explanation how the regex pattern was created.
My String gets returned from a DataMatrix scanner. For example
String contained = "~ak4,0000D"
Now I want to test this String, if it matches the pattern from the regex.
The String starts everytime with the "~".
After this, two lower cased charactes follow in this example "ak".
After this, there follows a six character long value "4,0000". Main problem here, because the comma can sit anywhere in this value, but the comma must be contained in it. For example it can be ",16000" or "150,00" or "2,8000".
At the last position there must be one of this characters A B C D E F G H J K L M in uppercase contained.
I hope some of you guys can help me.

The regex would be ~[a-z]{2}(?=[\d\,]{6})((\d)*\,(\d)*)[A-H|J-M]{1}$ You can create and test expressions here
boolean isMatch(String STRING_YOU_WANT_TO_MATCH)
{
Pattern patt = Pattern.compile(YOUR_REGEX_PATTERN);
Matcher matcher = patt.matcher(STRING_YOU_WANT_TO_MATCH);
return matcher.matches();
}

You need to use a positive lookahead based regex like below.
System.out.println("~ak4,0000D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~fk,10000D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~jk400,00D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~ak4,0000D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~fk10000,D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~jk400,00I".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~ak40000,Z".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~fky,10000D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
System.out.println("~,jk40000D".matches("~[a-z]{2}(?=\\d*,\\d*.$)[\\d,]{6}[A-HJ-M]"));
Output:
true
true
true
true
true
false
false
false
false

One thing you need to know about regular expressions are that they are a family of things, not one specific thing. There are rather a lot of distinct but similar regular expression languages, and the facilities supporting them vary from programming language to programming language.
Here is a regex pattern that will work in most regex languages to match your strings:
"^~[a-z][a-z]((,[0-9][0-9][0-9][0-9][0-9])|([0-9],[0-9][0-9][0-9][0-9])|([0-9][0-9],[0-9][0-9][0-9])|([0-9][0-9][0-9],[0-9][0-9])|([0-9][0-9][0-9][0-9],[0-9])|([0-9][0-9][0-9][0-9][0-9],))[A-HJ-M]$"
The '^' anchors the pattern to the beginning of the string, and the '$' anchors it to the end, so that the pattern must match the whole string as opposed to a substring. Characters enclosed in square brackets represent "character classes" matching exactly one character from among a set, with the two characters separated by a '-' representing a range of characters. The '|' separates alternatives, and parentheses serve to group subpatterns. For some regex engines, the parentheses and '\' symbols need to be escaped via a preceeding '\' character to have these special meanings instead of representing themselves.
A more featureful regex language can allow that to be greatly simplified; for example:
"^~[a-z]{2}[0-9,]{6}(?<=[a-z][0-9]*,[0-9]*)[A-HJ-M]$"
The quantifiers "{2}" and "{6}" designate that the preceding subpattern must match exactly the specified number of times (instead of once), and the quantifier "*" designates that the preceding subpattern may match any number of times, including zero. Additionally, the "(?<= ...)" is a zero-length look-behind assertion, which tests whether the previous characters of the input match the given sub-pattern (in addition to having already matched the preceding sub-pattern); the characters must also match the subsequent sub-pattern (which does consume them). The '.' metacharacter and '*' quantifier are supported in pretty much all regex languages, but assertions and curly-brace quantifiers are less widely supported. Java's and Perl's regular expression languages will both understand this pattern, however.

~[a-z]{2}[\d|\,]{6}[A-M]
I'm no pro at regex though,but I used this site everytime to build my pattern:
RegExr
Use it like this in your code:
Pattern pattern = Pattern.compile(yourPatternAsAString);
Matcher matcher = pattern.matcher(yourInputToMatch);
if(matcher.matches()) {
// gogogo
}

Android Regular Expression - Replace all spaces '(' ')' '-'

I newt o regular expressions and been using tutorials, but the regular express I have works sometimes, but doesn't all the time. I am getting my numbers out of the contact list from my android phone. I am trying to get rid of all spaces, '(', ')', and '-'
For example:
1. (555) 867-5309 -> 5558675309
2. 1555-555-5555 -> 15555555555
3. 555-555-5555 -> 5555555555
This is the line I am using
String formatphone = contactPhone.replaceAll("\\s()-","");
For some numbers it only returns number and sometimes it doesn't change the format.
Is it correct? Do i need to format something because I am taking it out of the phone's contact list?

Put the desired characters in a character class:
String formatphone = contactPhone.replaceAll("[ ()-]","");
Ensure that you put the hyphen - at either end.

Try using this:
String formatphone = contactPhone.replaceAll("^.*[\\s\\(\\)-].*", "");
As a regular expression you're defining a set using []. In that set you include any character you want to be replaced. As ( and ) are special meaning characters, you have to escape them. As the - is a special character used to design ranges, it has to be the last character of your set, so if nothing is behind it, it's not a range, but just that character (you could escape it too, though).

What regex can be used to filter out dalvikvm AND dalvikvm-heap messages from the logcat

Using this link I was able to create a filter using the regex (?!dalvikvm\b)\b\w+ to filter out messages with the tag dalvikvm, but I have tried several variations of the regex such as (?!dalvikvm-heap\b)\b\w+, (?!dalvikvm\\-heap\b)\b\w+, (?!dalvikvm[-]heap\b)\b\w+, and many others and I can't seem to get rid of the dalvikvm-heap messages. Ideally I would like to filter them both, but I haven't figured that part out yet either.
Any help would be appreciated.

Use ^(?!dalvikvm) in the tag field instead. That will show only messages whose tag doesn't start with "dalvikvm".
The below is notes about how this works; you can skip them if you're not interested. To start, you have to remember that the question, "Does this string match the regex?" really means, "Is there any position in this string where the regex matches?"
The tricky thing about (?!x) negative assertions is that they match wherever the next part of the string doesn't match x: but that's true of every place in the string "dalvikvm" except the start. The blog post you linked to adds a \b at the end so that the expression matches only at a place that's not just before "dalvikvm" and is a word boundary. But this would still match, because the end of the string is a word boundary, and it doesn't have "dalvikvm" after it. So the blog post adds the \w+ after it, to say that after the word boundary there have to be more word characters.
It works for exactly that case, but it's a bit of an odd way of making a regex, and it's relatively expensive to evaluate. And as you've noticed, you can't adapt it to (?!dalvikvm-heap\b)\b\w+. "-" is a non-word character, so immediately after it, there is a word boundary, followed by word characters, and not followed by "dalvikvm-heap", so the regex matches at that point.
Instead, I use ^, which only matches at the start of the string, along with the negative assertion. Overall, the regex only matches at the start of the string, and only then if the start of the string isn't followed by "dalvikvm". That means it won't match "dalvikvm" or "dalvikvm-heap". It's also cheaper to evaluate, because the regex engine knows it can only possibly match at the start.
Making the regex this way, you can filter out multiple tags by just putting them together. For example, ^(?!dalvikvm)(?!IInputConnectionWrapper) will filter out tags that start with "dalvikvm" or "IInputConnectionWrapper", because the start of the string has to not be followed by the first and not be followed by the second.
BTW, thanks for your link. I didn't realise that you could use the logcat filters that way, so I wouldn't have come up with my answer without it.