Question

Basically I have an HTML fragment with <br> and <p></p> inside. I was able to remove all the HTML tags but doing so leaves the text in a bad format.

I want something like nl2br() in PHP except reverse the input and output and also takes into account <p> tags. is there a library for it in Java?

Answer 1

You basically need to replace each <br> with \n and each <p> with \n\n. So, at the points where you succeed to remove them, you need to insert the \n and \n\n respectively.

Here’s a kickoff example with help of the Jsoup HTML parser (the HTML example is intentionally written that way so that it’s hard if not nearly impossible to use regex for this).

public static void main(String[] args) throws Exception {
    String originalHtml = "<p>p1l1<br/><!--</p>-->p1l2<br><!--<p>--></br><p id=p>p2l1<br class=b>p2l2</p>";
    String text = br2nl(originalHtml);
    String newHtml = nl2br(text);

    System.out.println("-------------");
    System.out.println(text);
    System.out.println("-------------");
    System.out.println(newHtml);
}

public static String br2nl(String html) {
    Document document = Jsoup.parse(html);
    document.select("br").append("\\n");
    document.select("p").prepend("\\n\\n");
    return document.text().replace("\\n", "\n");
}

public static String nl2br(String text) {
    return text.replace("\n\n", "<p>").replace("\n", "<br>");
}

(note: replaceAll() is unnecessary as we just want a simple charsequence-by-charsequence replacement here, not regexpattern-by-charsequence replacement)

Output:

<p>p1l1<br/><!--</p>-->p1l2<br><!--<p>--></br><p id=p>p2l1<br class=b>p2l2</p>
-------------


p1l1 
p1l2 



p2l1 
p2l2
-------------
<p>p1l1 <br>p1l2 <br> <br> <p>p2l1 <br>p2l2

A bit hacky, but it works.