Trying to remove a lot of unicodes from a string but having issues with regex in java.
Example text:
\u2605 StatTrak\u2122 Shadow Daggers
Example Desired Result:
StatTrak Shadow Daggers
The current regex code I have that will not work:
list.replaceAll("\\\\u[0-9]+","");
The code will execute but the text will not be replaced. From looking at other solutions people seem to use only two "\\" but anything less than 4 throws me the typical error:
Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal Unicode escape sequence near index 2
\u[0-9]+
I've tried the current regex solution in online test environments like RegexPlanet and FreeFormatter and both give the correct result.
Any help would be appreciated.
Assuming that you would like to replace a "special string" to empty String. As I see, \u2605 and \u2122 are POSIX character class. That's why we can try to replace these printable characters to "". Then, the result is the same as your expectation.
Sample would be:
list = list.replaceAll("\\P{Print}", "");
Hope this help.
In Java, something like your \u2605 is not a literal sequence of six characters, it represents a single unicode character — therefore your pattern "\\\\u[0-9]{4}" will not match it.
Your pattern describes a literal character \ followed by the character u followed by exactly four numeric characters 0 through 9 but what is in your string is the single character from the unicode code point 2605, the "Black Star" character.
This is just as other escape sequences: in the string "some\tmore" there is no character \ and there is no character t ... there is only the single character 0x09, a tab character — because it is an escape sequence known to Java (and other languages) it gets replaced by the character that it represents and the literal \ t are no longer characters in the string.
Kenny Tai Huynh's answer, replacing non-printables, may be the easiest way to go, depending on what sorts of things you want removed, or you could list the characters you want (if that is a very limited set) and remove the complement of those, such as mystring.replaceAll("[^A-Za-z0-9]", "");
I'm an idiot. I was calling the replaceAll on the string but not assigning it as I thought it altered the string anyway.
What I had previously:
list.replaceAll("\\\\u[0-9]+","");
What I needed:
list = list.replaceAll("\\\\u[0-9]+","");
Result works fine now, thanks for the help.
Is there a special regex statement like \w that denotes all printable characters? I'd like to validate that a string only contains a character that can be printed--i.e. does not contain ASCII control characters like \b (bell), or null, etc. Anything on the keyboard is fine, and so are UTF chars.
If there isn't a special statement, how can I specify this in a regex?
Very late to the party, but this regexp works: /[ -~]/.
How? It matches all characters in the range from space (ASCII DEC 32) to tilde (ASCII DEC 126), which is the range of all printable characters.
If you want to strip non-ASCII characters, you could use something like:
$someString.replace(/[^ -~]/g, '');
NOTE: this is not valid .net code, but an example of regexp usage for those who stumble upon this via search engines later.
If your regex flavor supports Unicode properties, this is probably the best the best way:
\P{Cc}
That matches any character that's not a control character, whether it be ASCII -- [\x00-\x1F\x7F] -- or Latin1 -- [\x80-\x9F] (also known as the C1 control characters).
The problem with POSIX classes like [:print:] or \p{Print} is that they can match different things depending on the regex flavor and, possibly, the locale settings of the underlying platform. In Java, they're strictly ASCII-oriented. That means \p{Print} matches only the ASCII printing characters -- [\x20-\x7E] -- while \P{Cntrl} (note the capital 'P') matches everything that's not an ASCII control character -- [^\x00-\x1F\x7F]. That is, it matches any ASCII character that isn't a control character, or any non-ASCII character--including C1 control characters.
TLDR Answer
Use this Regex...
\P{Cc}\P{Cn}\P{Cs}
Working Demo
In this demo, I use this regex to search the string "Hello, World!_". I'm going to add a weird character at the end, (char)4 — this is the character for END TRANSMISSION.
using System;
using System.Text.RegularExpressions;
public class Test {
public static void Main() {
// your code goes here
var regex = new Regex(#"![\P{Cc}\P{Cn}\P{Cs}]");
var matches = regex.Matches("Hello, World!" + (char)4);
Console.WriteLine("Results: " + matches.Count);
foreach (Match match in matches) {
Console.WriteLine("Result: " + match);
}
}
}
Full Working Demo at IDEOne.com
TLDR Explanation
\P{Cc} : Do not match control characters.
\P{Cn} : Do not match unassigned characters.
\P{Cs} : Do not match UTF-8-invalid characters.
Alternatives
\P{C} : Match only visible characters. Do not match any invisible characters.
\P{Cc} : Match only non-control characters. Do not match any control characters.
\P{Cc}\P{Cn} : Match only non-control characters that have been assigned. Do not match any control or unassigned characters.
\P{Cc}\P{Cn}\P{Cs} : Match only non-control characters that have been assigned and are UTF-8 valid. Do not match any control, unassigned, or UTF-8-invalid characters.
\P{Cc}\P{Cn}\P{Cs}\P{Cf} : Match only non-control, non-formatting characters that have been assigned and are UTF-8 valid. Do not match any control, unassigned, formatting, or UTF-8-invalid characters.
Source and Explanation
Take a look at the Unicode Character Properties available that can be used to test within a regex. You should be able to use these regexes in Microsoft .NET, JavaScript, Python, Java, PHP, Ruby, Perl, Golang, and even Adobe. Knowing Unicode character classes is very transferable knowledge, so I recommend using it!
All Matchable Unicode Character Sets
If you want to know any other character sets available, check out regular-expressions.info...
\p{L} or \p{Letter}: any kind of letter from any language.
\p{Ll} or \p{Lowercase_Letter}: a lowercase letter that has an uppercase variant.
\p{Lu} or \p{Uppercase_Letter}: an uppercase letter that has a lowercase variant.
\p{Lt} or \p{Titlecase_Letter}: a letter that appears at the start of a word when only the first letter of the word is capitalized.
\p{L&} or \p{Cased_Letter}: a letter that exists in lowercase and uppercase variants (combination of Ll, Lu and Lt).
\p{Lm} or \p{Modifier_Letter}: a special character that is used like a letter.
\p{Lo} or \p{Other_Letter}: a letter or ideograph that does not have lowercase and uppercase
\p{M} or \p{Mark}: a character intended to be combined with another character (e.g. accents, umlauts, enclosing boxes, etc.).
\p{Mn} or \p{Non_Spacing_Mark}: a character intended to be combined with another
character without taking up extra space (e.g. accents, umlauts, etc.).
\p{Mc} or \p{Spacing_Combining_Mark}: a character intended to be combined with another character that takes up extra space (vowel signs in many Eastern languages).
\p{Me} or \p{Enclosing_Mark}: a character that encloses the character it is combined with (circle, square, keycap, etc.).
\p{Z} or \p{Separator}: any kind of whitespace or invisible separator.
\p{Zs} or \p{Space_Separator}: a whitespace character that is invisible, but does take up space.
\p{Zl} or \p{Line_Separator}: line separator character U+2028.
\p{Zp} or \p{Paragraph_Separator}: paragraph separator character U+2029.
\p{S} or \p{Symbol}: math symbols, currency signs, dingbats, box-drawing characters, etc.
\p{Sm} or \p{Math_Symbol}: any mathematical symbol.
\p{Sc} or \p{Currency_Symbol}: any currency sign.
\p{Sk} or \p{Modifier_Symbol}: a combining character (mark) as a full character on its own.
\p{So} or \p{Other_Symbol}: various symbols that are not math symbols, currency signs, or combining characters.
\p{N} or \p{Number}: any kind of numeric character in any script.
\p{Nd} or \p{Decimal_Digit_Number}: a digit zero through nine in any script except ideographic scripts.
\p{Nl} or \p{Letter_Number}: a number that looks like a letter, such as a Roman numeral.
\p{No} or \p{Other_Number}: a superscript or subscript digit, or a number that is not a digit 0–9 (excluding numbers from ideographic scripts).
\p{P} or \p{Punctuation}: any kind of punctuation character.
\p{Pd} or \p{Dash_Punctuation}: any kind of hyphen or dash.
\p{Ps} or \p{Open_Punctuation}: any kind of opening bracket.
\p{Pe} or \p{Close_Punctuation}: any kind of closing bracket.
\p{Pi} or \p{Initial_Punctuation}: any kind of opening quote.
\p{Pf} or \p{Final_Punctuation}: any kind of closing quote.
\p{Pc} or \p{Connector_Punctuation}: a punctuation character such as an underscore that connects words.
\p{Po} or \p{Other_Punctuation}: any kind of punctuation character that is not a dash, bracket, quote or connector.
\p{C} or \p{Other}: invisible control characters and unused code points.
\p{Cc} or \p{Control}: an ASCII or Latin-1 control character: 0x00–0x1F and 0x7F–0x9F.
\p{Cf} or \p{Format}: invisible formatting indicator.
\p{Co} or \p{Private_Use}: any code point reserved for private use.
\p{Cs} or \p{Surrogate}: one half of a surrogate pair in UTF-16 encoding.
\p{Cn} or \p{Unassigned}: any code point to which no character has been assigned.
There is a POSIX character class designation [:print:] that should match printable characters, and [:cntrl:] for control characters. Note that these match codes throughout the ASCII table, so they might not be suitable for matching other encodings.
Failing that, the expression [\x00-\x1f] will match through the ASCII control characters, although again, these could be printable in other encodings.
In Java, the \p{Print} option specifies the printable character class.
It depends wildly on what regex package you are using. This is one of these situations about which some wag said that the great thing about standards is there are so many to choose from.
If you happen to be using C, the isprint(3) function/macro is your friend.
Adding on to #Alan-Moore, \P{Cc} is actually as example of Negative Unicode Category or Unicode Block (ref: Character Classes in Regular Expressions). \P{name} matches any character that does not belong to a Unicode general category or named block. See the referred link for more examples of named blocks supported in .Net
I have a regex expression which removes all non alphanumeric characters. It is working fine for all special characters apart from ^. Below is the regex expression I am using.
String strRefernce = strReference.replaceAll("[^\\p{IsAlphabetic}^\\p{IsDigit}]", "").toUpperCase();
I tried modifying it to
String strRefernce = strReference.replaceAll("[^\\p{IsAlphabetic}^\\p{IsDigit}]\\^", "").toUpperCase();
and
String strRefernce = strReference.replaceAll("[^\\p{IsAlphabetic}^\\p{IsDigit}\\^]", "").toUpperCase();
But these are also not able to remove this symbol.
Can someone please help me with this.
The first ^ inside [^...] is a negation mark making the character class a negated one (matching characters other than what is inside).
The second one inside is considered a literal - thus, it should not be matched with the regex. Remove it, and a caret will get matched with it:
"[^\\p{IsAlphabetic}\\p{IsDigit}]"
or even shorter:
"(?U)\\P{Alnum}"
The \P{Alnum} class stands for any character other than an alphanumeric character: [\p{Alpha}\p{Digit}] (see Java regex reference). When you pass (?U), the \P{Alnum} class will not match Unicode letters. See this IDEONE demo.
Add a + at the end if you want to remove whole chunks of symbols other than \\p{IsAlphabetic} and \\p{IsDigit}.
This works as well.
System.out.println("Text 尖酸[刻薄 ^, More _0As text °ÑÑ"".replaceAll("(?U)[^[\\W_]]+", " "));
Output
Text 尖酸 刻薄 More 0As text Ñ Ñ
Not sure but the word might be the more comprehensive list of alphanum characters.
[\\W_] is a class containing non-words and an underscore.
When put into a negative Java class construct it becomes
[^[\\W_]] is a negative class of a union between nothing and
a class containing non-words and an underscore.
I have string like below
"them coming \nLove it \ud83d\ude00"
I want to remove this character "\ud83d\ude00". so it will be
"them coming \nLove it "
How can I achieve this in java? I have tried with code like below but it won't works
payload.toString().replaceAll("\\\\u\\b{4}.", "")
Thanks :)
I think \\\\u\\b{4}. will not work, because regex treat \ud83d as a symbol �, not a literal string. So to match this kind unwanted (for any reason) unicode characters it will be better to exclude character you accept(don't want to replace), so for ecample all ASCII character, and match everything else (what you want to replace). Try with:
[^\x00-\x7F]+
The \x00-\x7F includes Unicode Basic Latin block.
String str = "them coming \nLove it \ud83d\ude00";
System.out.println(str.replaceAll("[^\\x00-\\x7F]+", ""));
will result with:
them coming
Love it
However, you willl hava a problem, if you use national character, any other non-ASCII symbols (ś,ą,♉,☹,etc.).
I have a regex that blocks invalid characters in a string, but it's also blocking chinese characters and i dont want it. Please help me with it. Below is the regex string that I am using.
String re = "[^\\x09\\x0A\\x0D\\x20-\\xD7FF\\xE000-\\xFFFD\\x10000-x10FFFF]";
Thanks in anticipation!
Since Java 7 you can make use of Unicode properties/scripts.
E.g. you can use the property \p{L} to match a letter in any language. Or the script \p{IsHiragana} to match a character contained in Hiragana. You need to check what script is fitting your needs.
See here on docs.Oracle.com for more details about regex and Unicode
It is also possible to match for the opposite, e.g. \P{L} is matching every character, that is NOT a letter, or you just add \p{L} to your negated character class, instead of the ranges that should define letters.