Develop Reference

Java won't replace all strings, because there is text next to the tags (post improved)

I'm working on a program, which formats HTML Code, extracted from a PDF file.
I have a String list, which contains paragraphs and is divided by that.
As the PDF has hyperlinks, I decided to replace them with a foot note number "[1]".
This will be used for citation of sources. I will eventually plan, to put it at the end of a paragraph, or sentence, so you can look up the sources, like you would in a book.
My Problem
For some reason not all the hyperlinks are replaced.
The reason is most likely, that there is text directly next to the tag.
Hell<a href="http://www.example.com">o old chap!
Specifically the "o" part and the "hell" part is blocking the java .replaceAll function, from doing it's job.
Expected Result
Hello [1] old chap!
EDIT:
If I would just add space, before and after the URL, it might split some words like "help", into "hel p", which is also not an option.
My code would have to replace the URL tag (without the ) and create no new extra spaces.
This is some of my code, where the problem occures:
for (int i = 0; i < EN.length; i++) {
Pattern pattern_URL = Pattern.compile("<a(.+?)\">", Pattern.DOTALL);
Matcher matcher_URL = pattern_URL.matcher(EN[i]); //Checks in the curren Array part.
if (matcher_URL.find() == true) {
source_number++;
String extractedURL = matcher_URL.group(0);
//System.out.println(extractedURL);
String extractedURL_fully = extractedURL.replaceAll("href=\"", ""); //Anführungszeichen
//System.out.println(extractedURL_fully);
String nobracketURL = extractedURL.replaceAll("\\)", ""); //Remove round brackets from URL
EN[i] = EN[i].replaceAll("\\)\"", "\""); /*Replace round brackets from URL in Array. (For some reasons there have been href URLs, with an bracket at the end. This was already in the PDF. They were causing massive problems, because it didn't comment them out, so the entire replaceAll command didn't function.)*/
EN[i] = EN[i].replaceAll(nobracketURL, "[" + source_number + "]"); //Replace URL tags with number and Edgy brackets
}
else{
//System.out.println("FALSE: " + "[" + i + "]");
}
}
The whole idea of this is, that it loops through the array and replaces all the URLs, including it's starting tag <a until the end of the starting tag "> (which can also be seen in the pattern regex.)

Correct me if I'm wrong, but what you need is to eliminate all the <a> tags from a given string, right? If that's the case all you needed to do was use a code like the following:
final String string = "<a href=\"http://www.example.com\">Sen";
final Pattern pattern = Pattern.compile("<a(.+?)>", Pattern.DOTALL);
final Matcher matcher = pattern.matcher(string);
final String result = matcher.replaceAll("");
System.out.println(result); // prints "Sen"
Notice I didn't use the replaceAll from the String object, but from the Matcher object. This replaces all matches for the empty string "".

Regular expression to match any characters including line breaks in a string using java

I have a string which includes line breaks in java .I need a regular expression to match any characters including line breaks.
Here is the string:
String s= "Hello World".(line break)
Note= amount"
I am using this (.*?) but it won't match line breaks.

You can try with this pattern:
([a-zA-Z\n])+
Tested on regexr. This is an example of how to implement it in Java
String pattern = "([a-zA-Z\n])+";
String input = "String with \n line break.";
Pattern p = Pattern.compile(pattern);
java.util.regex.Matcher m = p.matcher(input);

Java Regex ReplaceAll with grouping

I want to surround all tokens in a text with tags in the following manner:
Input: " abc fg asd "
Output:" <token>abc</token> <token>fg</token> <token>asd</token> "
This is the code I tried so far:
String regex = "(\\s)([a-zA-Z]+)(\\s)";
String text = " abc fg asd ";
text = text.replaceAll(regex, "$1<token>$2</token>$3");
System.out.println(text);
Output:" <token>abc</token> fg <token>asd</token> "
Note: for simplicity we can assume that the input starts and ends with whitespaces

Use lookaround:
String regex = "(?<=\\s)([a-zA-Z]+)(?=\\s)";
...
text = text.replaceAll(regex, "<token>$1</token>");

If your tokens are only defined with a character class you don't need to describe what characters are around. So this should suffice since the regex engine walks from left to right and since the quantifier is greedy:
String regex = "[a-zA-Z]+";
text = text.replaceAll(regex, "<token>$0</token>");

// meaning not a space, 1+ times
String result = input.replaceAll("([^\\s]+)", "<token>$1</token>");
this matches everything that isn't a space. Prolly the best fit for what you need. Also it's greedy meaning it will never leave out a character that it shouldn't ( it will never find the string "as" in the string "asd" when there is another character with which it matches)

Pattern/Matcher in Java?

I have a certain text in Java, and I want to use pattern and matcher to extract something from it. This is my program:
public String getItemsByType(String text, String start, String end) {
String patternHolder;
StringBuffer itemLines = new StringBuffer();
patternHolder = start + ".*" + end;
Pattern pattern = Pattern.compile(patternHolder);
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
itemLines.append(text.substring(matcher.start(), matcher.end())
+ "\n");
}
return itemLines.toString();
}
This code works fully WHEN the searched text is on the same line, for instance:
String text = "My name is John and I am 18 years Old";
getItemsByType(text, "My", "John");
immediately grabs the text "My name is John" out of the text. However, when my text looks like this:
String text = "My name\nis John\nand I'm\n18 years\nold";
getItemsByType(text, "My", "John");
It doesn't grab anything, since "My" and "John" are on different lines. How do I solve this?

Use this instead:
Pattern.compile(patternHolder, Pattern.DOTALL);
From the javadoc, the DOTALL flag means:
Enables dotall mode.
In dotall mode, the expression . matches any character, including a line terminator. By default this expression does not match line terminators.

Use Pattern.compile(patternHolder, Pattern.DOTALL) to compile the pattern. This way the dot will match the newline. By default, newline is treated in a special way and not matched by the dot.

Java Regex - How to replace a pattern or how to

I have a bunch of HTML files. In these files I need to correct the src attribute of the IMG tags.
The IMG tags look typically like this:
<img alt="" src="./Suitbert_files/233px-Suitbertus.jpg" class="thumbimage" height="243" width="233" />`
where the attributes are NOT in any specific order.
I need to remove the dot and the forward slash at the beginning of the src attribute of the IMG tags so they look like this:
<img alt="" src="Suitbert%20%E2%80%93%20Wikipedia_files/233px-Suitbertus.jpg" class="thumbimage" height="243" width="233" />
I have the following class so far:
import java.util.regex.*;
public class Replacer {
// this PATTERN should find all img tags with 0 or more attributes before the src-attribute
private static final String PATTERN = "<img\\.*\\ssrc=\"\\./";
private static final String REPLACEMENT = "<img\\.*\\ssrc=\"";
private static final Pattern COMPILED_PATTERN = Pattern.compile(PATTERN, Pattern.CASE_INSENSITIVE);
public static void findMatches(String html){
Matcher matcher = COMPILED_PATTERN.matcher(html);
// Check all occurance
System.out.println("------------------------");
System.out.println("Following Matches found:");
while (matcher.find()) {
System.out.print("Start index: " + matcher.start());
System.out.print(" End index: " + matcher.end() + " ");
System.out.println(matcher.group());
}
System.out.println("------------------------");
}
public static String replaceMatches(String html){
//Pattern replace = Pattern.compile("\\s+");
Matcher matcher = COMPILED_PATTERN.matcher(html);
html = matcher.replaceAll(REPLACEMENT);
return html;
}
}
So, my method findMatches(String html) seems to find correctly all IMG tags where the src attributes starts with ./.
Now my method replaceMatches(String html) does not correctly replace the matches.
I am a newbie to regex, but I assume that either the REPLACEMENT regex is incorrect or the usage of the replaceAll method or both.
A you can see, the replacement String contains 2 parts which are identical in all IMG tags:
<img and src="./. In between these 2 parts, there should be the 0 or more HTML attributes from the original string.
How do I formulate such a REPLACEMENT string?
Can somebody please enlighten me?

Don't use regex for HTML. Use a parser, obtain the src attribute and replace it.

Try these:
PATTERN = "(<img[^>]*\\ssrc=\")\\./"
REPLACEMENT = "$1"
Basically, you capture everything except the ./ in group #1, then plug it back in using the $1 placeholder, effectively stripping off the ./.
Notice how I changed your .* to [^>]*, too. If there happened to be two IMG tags on the same line, like this:
<img src="good" /><img src="./bad" />
...your regex would match this:
<img src="good" /><img src="./
It would do that even if you used a non-greedy .*?. [^>]* makes sure the match is always contained within the one tag.

Your replacement is incorrect. It will replace the matched string by the replacement (not interpreted as a regexp). If you want to achieve, what you want, you need to use groups. A group is delimited by the parenthesis of the regexp. Each opening parenthesis indicates a new group.
You can use $i in the replacement string to reproduce what a groupe has matched and where 'i' is your group number reference. See The doc of appendReplacement for the details.
// Here is an example (it looks a bit like your case but not exactly)
String input = "<img name=\"foobar\" src=\"img.png\">";
String regexp = "<img(.+)src=\"[^\"]+\"(.*)>";
Matcher m = Pattern.compile(regexp).matcher(input);
StringBuffer sb = new StringBuffer();
while(m.find()) {
// Found a match!
// Append all chars before the match and then replaces the match by the
// replacement (the replacement refers to group 1 & 2 with $1 & $2
// which match respectively everything between '<img' and 'src' and,
// everything after the src value and the closing >
m.appendReplacement(sb, "<img$1src=\"something else\"$2>";
}
m.appendTail(sb);// No more match, we append the end of input
Hope this helps you

If src attributes only occur in your HTML within img tags, you can just do this:
input.replace("src=\"./", "src=\"")
You could also do this without java by using sed if you're using a *nix OS