I'm implementing a keyword highlighter in Java. I'm using java.util.regex.Pattern to highlight (making bold) keyword within String content. The following piece of code is working fine for alphanumeric keywords, but it is not working for some special characters. For example, in String content, I would like to highlight the keyword c++ which has the special character + (plus), but it's not getting highlighted properly. How do I escape + character so that c++ is highlighted?
public static void main(String[] args)
{
String content = "java,c++,ejb,struts,j2ee,hibernate";
System.out.println("CONTENT: " + content);
String highlight = "C++";
System.out.println("HIGHLIGHT KEYWORD: " + highlight);
//highlight = highlight.replaceAll(Pattern.quote("+"), "\\\\+");
java.util.regex.Pattern pattern = java.util.regex.Pattern.compile("\\b" + highlight + "\\b", java.util.regex.Pattern.CASE_INSENSITIVE);
System.out.println("PATTERN: " + pattern.pattern());
java.util.regex.Matcher matcher = pattern.matcher(content);
while (matcher.find()) {
System.out.println("Match found!!!");
for (int i = 0; i <= matcher.groupCount(); i++) {
System.out.println(matcher.group(i));
content = matcher.replaceAll("<B>" + matcher.group(i) + "</B>");
}
}
System.out.println("RESULT: " + content);
}
Output:
CONTENT: java,c++,ejb,struts,j2ee,hibernate
HIGHLIGHT KEYWORD: C++
PATTERN: \bC++\b
Match found!!!
c
RESULT: java,c++,ejb,struts,j2ee,hibernate
I even tried to escape '+' before calling Pattern.compile like this,
highlight = highlight.replaceAll(Pattern.quote("+"), "\\\\+");
but still I'm not able to get the syntax right. Can somebody help me solve this?
This should do what you need:
Pattern pattern = Pattern.compile(
"\\b"
+ Pattern.quote(highlight)
+ "\\b",
Pattern.CASE_INSENSITIVE);
Update: you are right, the above doesn't work for C++ (\b matches word boundaries and doesn't recognize ++ as a word). We need a more complicated solution:
Pattern pattern = Pattern.compile(
"\\b"
+ Pattern.quote(highlight)
+ "(?![^\\p{Punct}\\s])", // matches if the match is not followed by
// anything other than whitespace or punctuation
Pattern.CASE_INSENSITIVE);
Update in response to comments: it seems that you need more logic in your pattern creation. Here's a helper method to create the pattern for you:
private static final String WORD_BOUNDARY = "\\b";
// edit this to suit your neds:
private static final String ALLOWED = "[^,.!\\-\\s]";
private static final String LOOKAHEAD = "(?!" + ALLOWED + ")";
private static final String LOOKBEHIND = "(?<!" + ALLOWED + ")";
public static Pattern createHighlightPattern(final String highlight) {
final Pattern pattern = Pattern.compile(
(Character.isLetterOrDigit(highlight.charAt(0))
? WORD_BOUNDARY : LOOKBEHIND)
+ Pattern.quote(highlight)
+ (Character.isLetterOrDigit(highlight.charAt(highlight.length() - 1))
? WORD_BOUNDARY : LOOKAHEAD),
Pattern.CASE_INSENSITIVE);
return pattern;
}
And here is some test code to check that it works:
private static void testMatch(final String haystack, final String needle) {
final Matcher matcher = createHighlightPattern(needle).matcher(haystack);
if (!matcher.find())
System.out.println("Failed to find pattern " + needle);
while (matcher.find())
System.out.println("Found additional match: " + matcher.group() +
" for pattern " + needle);
}
public static void main(final String[] args) {
final String testString = "java,c++,hibernate,.net,asp.net,c#,spring";
testMatch(testString, "java");
testMatch(testString, "c++");
testMatch(testString, ".net");
testMatch(testString, "c#");
}
When I run this method, I don't see any output (which is good :-))
The problem is that the \b word boundary anchor is not matching, because + is a non word character and I assume there is a whitespace following that is also a non word character.
A word boundary \b is matching a change from a word character (Member in \w) to a non word character (no member of \w).
Also if you want to match a + literally you have to escape it. Here you are searching for C++ that means match at least one C and the ++ is a possessive quantifier matching at least 1 C and does not backtrack.
Try changing your pattern to something like this
java.util.regex.Pattern.compile("\\b" + highlight + "(?=\s)", java.util.regex.Pattern.CASE_INSENSITIVE);
(?=\s) is a positive lookahead that will check if there is a whitespace following your highlight
Additionally you will need to esacape the + your are searching for.
All you need is here :
Pattern.compile("\\Q"+highlight+"\\E", java.util.regex.Pattern.CASE_INSENSITIVE);
Assuming your keyword does not begin or end with punctuation, here is a commented regex which uses lookahead and lookbehind to achieve your desired matching behavior:
// Compile regex to match a keyword or keyphrase.
java.util.regex.Pattern pattern = java.util.regex.Pattern.compile(
"(?<=[\\s'\".?!,;:]|^) # Word preceded by ws, quote, punct or BOS.\n" +
// Escape any regex metacharacters in the keyword phrase.
java.util.regex.Pattern.quote(highlight) + " # Keyword to be matched.\n" +
"(?=[\\s'\".?!,;:]|$) # Word followed by ws, quote, punct or EOS.",
Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE | Pattern.COMMENTS);
Note that this solution works even if your keyword is a phrase containing spaces.
Related
Want to capture the string after the last slash and before either a (; sid=) word or a (?) character.
sample data:
sessionId=30a793b1-ed7e-464a-a630; Url=https://www.example.com/mybook/order/newbooking/itemSummary; sid=KJ4dgQGdhg7dDn1h0TLsqhsdfhsfhjhsdjfhjshdjfhjsfddscg139bjXZQdkbHpzf9l6wy1GdK5XZp; targetUrl=https://www.example.com/mybook/order/newbooking/page1?id=122;
sessionId=sfdsdfsd-ba57-4e21-a39f-34; Url=https://www.example.com/mybook/order/newbooking/itemList?id=76734¶=jhjdfhj&type=new&ordertype=kjkf&memberid=273647632&iSearch=true; sid=Q4hWgR1GpQb8xWTLpQB2yyyzmYRgXgFlJLGTc0QJyZbW targetUrl=https://www.example.com/ mybook/order/newbooking/page1?id=123;
sessionId=0e1acab1-45b8-sdf3454fds-afc1-sdf435sdfds; Url=https://www.example.com/mybook/order/newbooking/; sid=hkm2gRSL2t5ScKSJKSJn3vg2sfdsfdsfdsfdsfdfdsfdsfdsfvJZkDD3ng0kYTjhNQw8mFZMn; targetUrl=https://www.example.com/mybook/order/newbooking/page1?id=343;
Expecting the below output:
1. itemSummary
2. itemList
3. ''(empty string)
Have build the below regex to capture it but its 100% accurate. It is capturing some additional part.
Regex
Url=.*\/(.*)(; sid|\?)
Could you please help me to improve the regex to get desired output?
Thanks in advance!
You may use this regex in Java with a greedy match after Url=:
\bUrl=\S+/([^?;/]+)(?=; sid|\?)
RegEx Demo
RegEx Demo:
\b: Word boundary
Url=: Match text Url=
\S+/: Match 1+ non-whitespace characters followed by a /
([^?;/]+): Match 1+ of a character that not ? and ; and /
(?=; sid|\?): Lookahead to assert that we have ; sid or ? ahead
Alternative solution:
Used regex:
"^Url=.*/(\\w+|)$"
Regex in test bench and context:
public static void main(String[] args) {
String input1 = "sessionId=30a793b1-ed7e-464a-a630; "
+ "Url=https://www.example.com/mybook/order/newbooking/itemSummary; "
+ "sid=KJ4dgQGdhg7dDn1h0TLsqhsdfhsfhjhsdjfhjshdjfhjsfddscg139bjXZQdkbHpzf9l6wy1GdK5XZp; "
+ "targetUrl=https://www.example.com/mybook/order/newbooking/page1?id=122;";
String input2 = "sessionId=sfdsdfsd-ba57-4e21-a39f-34; "
+ "Url=https://www.example.com/mybook/order/newbooking/itemList?id=76734¶=jhjdfhj&type=new&ordertype=kjkf&memberid=273647632&iSearch=true; "
+ "sid=Q4hWgR1GpQb8xWTLpQB2yyyzmYRgXgFlJLGTc0QJyZbW "
+ "targetUrl=https://www.example.com/mybook/order/newbooking/page1?id=123;";
String input3 = "sessionId=0e1acab1-45b8-sdf3454fds-afc1-sdf435sdfds; "
+ "Url=https://www.example.com/mybook/order/newbooking/; "
+ "sid=hkm2gRSL2t5ScKSJKSJn3vg2sfdsfdsfdsfdsfdfdsfdsfdsfvJZkDD3ng0kYTjhNQw8mFZMn; "
+ "targetUrl=https://www.example.com/mybook/order/newbooking/page1?id=343;";
List<String> inputList = Arrays.asList(input1, input2, input3);
// Pre-compiled Patterns should not be in loops - that is why they are placed outside the loops
Pattern replaceWithNewLinePattern = Pattern.compile(";?\\s|\\?");
Pattern extractWordFromUrlPattern = Pattern.compile("^Url=.*/(\\w+|)$", Pattern.MULTILINE);
int count = 0;
for(String input : inputList) {
String inputWithNewLines = replaceWithNewLinePattern.matcher(input).replaceAll("\n");
// System.out.println(inputWithNewLines); // Check the change...
Matcher matcher = extractWordFromUrlPattern.matcher(inputWithNewLines);
while (matcher.find()) {
System.out.printf( "%d. '%s'%n", ++count, matcher.group(1));
}
}
}
Output:
1. 'itemSummary'
2. 'itemList'
3. ''
How can I get an mp3 url with REGEX?
This mp3 url, for example:
https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
This is a what I've tried so far but I want it to only accept a url with '.mp3' on the end.
(https?|ftp|file)://[-a-zA-Z0-9+&##/%?=~_|!:,.;]*[-a-zA-Z0-9+&##/%=~_|]
This expression would likely pass your desired inputs:
^(https?|ftp|file):\/\/(www.)?(.*?)\.(mp3)$
If you wish to add more boundaries to it, you can do that. For instance, you can add a list of chars instead of .*.
I have added several capturing groups, just to be simple to call, if necessary.
RegEx
If this wasn't your desired expression, you can modify/change your expressions in regex101.com.
RegEx Circuit
You can also visualize your expressions in jex.im:
const regex = /^(https?|ftp|file):\/\/(www.)?(.*?)\.(mp3)$/gm;
const str = `https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
http://soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
http://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
ftp://soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
file://localhost/examples/mp3/SoundHelix-Song-1.mp3
file://localhost/examples/mp3/SoundHelix-Song-1.wav
file://localhost/examples/mp3/SoundHelix-Song-1.avi
file://localhost/examples/mp3/SoundHelix-Song-1.m4a`;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Java Test
import java.util.regex.Matcher;
import java.util.regex.Pattern;
final String regex = "^(https?|ftp|file):\\/\\/(www.)?(.*?)\\.(mp3)$";
final String string = "https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3\n"
+ "http://soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3\n"
+ "http://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3\n"
+ "ftp://soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3\n"
+ "file://localhost/examples/mp3/SoundHelix-Song-1.mp3\n"
+ "file://localhost/examples/mp3/SoundHelix-Song-1.wav\n"
+ "file://localhost/examples/mp3/SoundHelix-Song-1.avi\n"
+ "file://localhost/examples/mp3/SoundHelix-Song-1.m4a";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
while (matcher.find()) {
System.out.println("Full match: " + matcher.group(0));
for (int i = 1; i <= matcher.groupCount(); i++) {
System.out.println("Group " + i + ": " + matcher.group(i));
}
}
If you want it to match inputs ending with '.mp3' you should add \.mp3$ at the end of your regex.
$ indicates the end of your expression
(https?|ftp|file):\/\/[-a-zA-Z0-9+&##\/%?=~_|!:,.;]*[-a-zA-Z0-9+&##\/%=~_|]\.mp3$
Matching:
https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3 **=> Match**
https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp4 **=> No Match**
You could use anchors to assert the start ^ and the end $ of the string and end the pattern with .mp3:
^https?://\S+\.mp3$
Explanation
^ Assert start of string
https?:// Match http with optional s and ://
\S+ Match 1+ times a non whitespace char
\.mp3 Match .mp3
$ Assert end of string
Regex demo | Java demo
For example:
String regex = "^https?://\\S+\\.mp3$";
String[] strings = {
"https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3",
"https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp4"
};
Pattern pattern = Pattern.compile(regex);
for (String s : strings) {
Matcher matcher = pattern.matcher(s);
if (matcher.find()) {
System.out.println(matcher.group(0));
}
}
Result
https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
Unable to implement regex for string in line starts with ? and ends with ;
appended with single quotes or double quotes.
for example:
?abcdef;
'?abcdef;'
"?abcdef;"
I tried a lot, like this "^\\?([^;]+)\\;$" but it did not work.
Test code snippet:
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexTest {
public static void main(final String[] args) {
final String text = "This is param-start ?abcdef; param-end";
final String patternString = "(['\"]?)\\?.*;\\1";
final Pattern pattern = Pattern.compile(patternString, Pattern.CASE_INSENSITIVE);
final Matcher matcher = pattern.matcher(text);
System.out.println("lookingAt = " + matcher.lookingAt());
System.out.println("matches = " + matcher.matches());
}
}
You may use this regex:
(["']?)\?.*;\1
For Java use:
final String pattern = "(['\"]?)\\?.*;\\1";
RegEx Demo
(["']?) matches an optional ' or " and captures in group #1
\1 is back-reference for the same value as in group #1
You may use
final String text = "This is param-start ?abcdef; param-end";
final String patternString = "(['\"]?)\\?.*?;\\1";
final Pattern pattern = Pattern.compile(patternString, Pattern.DOTALL);
final Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
System.out.println("Match found: " + matcher.group());
}
// => Match found: = ?abcdef;
See the Java demo and the regex demo. Regulex graph:
Notes:
while (matcher.find()) - iterates through all potential matches in the string
matcher.group() - accesses the match value.
Regex
(['"]?) - Capturing group 1: either ' or "
\? - a ? char
.*? - any 0+ chars, as few as possible (the pattern is compiled with Pattern.DOTALL, so it will match across line breaks, too)
; - a semi-colon
\1 - the same value as captured in Group 1.
Your description stated "starts with ? and ends with ;", but your sample string does not end with a semicolon - it's ending with wtih a double quote.
If you want to allow the string to start or end with either a single quote or double quote, your match should be:
^['"]?\?[^;]+;\['"]?$
I want to validate a username against these requirements:
Just accept character or digital
At least one character
I tried with
public boolean validateFormat(String input){
return Pattern.compile("^[A-Za-z0-9]+$").matcher(input).matches();
}
How can I do this one?
Try with this regex:
^(\w|\d)+$
^ indicates the start of the string
$ indicates the end of the string
\w means any word character
\d means any digit
| is the logical OR operator
Anyway, i suggest you to use an online regex tester like regex101.com .It is very helpful to quickly test regular expressions.
Hope it can help!
== UPDATE ==
In Java code:
final String regex = "^(\\w|\\d)+$";
final String string = "myCoolUsername12";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
if(matcher.matches()) {
// if you are interested only in matching the full regex
}
// Otherwise, you can iterate over the matched groups (including the full match)
while (matcher.find()) {
System.out.println("Full match: " + matcher.group(0));
for (int i = 1; i <= matcher.groupCount(); i++) {
System.out.println("Group " + i + ": " + matcher.group(i));
}
}
/^[A-Za-z0-9]+(?:[ _-][A-Za-z0-9]+)*$/
I had asked this question some times back here Regular expression that does not contain quote but can contain escaped quote and got the response, but somehow i am not able to make it work in Java.
Basically i need to write a regular expression that matches a valid string beginning and ending with quotes, and can have quotes in between provided they are escaped.
In the below code, i essentially want to match all the three strings and print true, but cannot.
What should be the correct regex?
Thanks
public static void main(String[] args) {
String[] arr = new String[]
{
"\"tuco\"",
"\"tuco \" ABC\"",
"\"tuco \" ABC \" DEF\""
};
Pattern pattern = Pattern.compile("\"(?:[^\"\\\\]+|\\\\.)*\"");
for (String str : arr) {
Matcher matcher = pattern.matcher(str);
System.out.println(matcher.matches());
}
}
The problem is not so much your regex, but rather your test strings. The single backslash before the internal quotes on your second and third example strings are consumed when the literal string is parsed. The string being passed to the regex engine has no backslash before the quote. (Try printing it out.) Here is a tested version of your function which works as expected:
import java.util.regex.*;
public class TEST
{
public static void main(String[] args) {
String[] arr = new String[]
{
"\"tuco\"",
"\"tuco \\\" ABC\"",
"\"tuco \\\" ABC \\\" DEF\""
};
//old: Pattern pattern = Pattern.compile("\"(?:[^\"\\\\]+|\\\\.)*\"");
Pattern pattern = Pattern.compile(
"# Match double quoted substring allowing escaped chars. \n" +
"\" # Match opening quote. \n" +
"( # $1: Quoted substring contents. \n" +
" [^\"\\\\]* # {normal} Zero or more non-quote, non-\\. \n" +
" (?: # Begin {(special normal*)*} construct. \n" +
" \\\\. # {special} Escaped anything. \n" +
" [^\"\\\\]* # more {normal} non-quote, non-\\. \n" +
" )* # End {(special normal*)*} construct. \n" +
") # End $1: Quoted substring contents. \n" +
"\" # Match closing quote. ",
Pattern.DOTALL | Pattern.COMMENTS);
for (String str : arr) {
Matcher matcher = pattern.matcher(str);
System.out.println(matcher.matches());
}
}
}
I've substituted your regex for an improved version (taken from MRE3). Note that this question gets asked a lot. Please see this answer where I compare several functionally equivalent expressions.