Java regex issue

Question

Requirement : String "richText" which can include plain text +anchor tag. The anchor tag is rewritten to modify its target, append JS, etc

Issue: The pattern matcher find() & appendReplacement() works fine till there is no special character "$" in the anchor tag. It throws an exception when $ is part of anchor tag.

Line 1 fixes up the exception part but creates an issue if "$" or "\" is present in plain text since plain text now has additional escape characters around the above 2 special characters(bcoz of quoteReplacement()). How do I strip the additional escape characters from plain text(undo affect of quoteReplacement)?

Method:

    String richText = Matcher.quoteReplacement(rText); //Line 1-escape characters   
    String anchorTagPattern = "<a[^>]*?href\\s*=[^>]*>(.*?)</a>";
    StringBuffer result = new StringBuffer(richText.length());
    Pattern pattern = Pattern.compile(anchorTagPattern);
    Matcher matcher = pattern.matcher(richText);
    while (matcher.find()) {
               String aTag = matcher.group();
               .......
               String formattedAnchorTag = rewriteTag(aTag);
               matcher.appendReplacement(result, formattedAnchorTag); ....
    }
    matcher.appendTail(result);
    //Plain text with $ \ has some additional escape characters because of Line 1. How    to remove them:

rText entered is

Plain text having $. Anchor tag to be rewritten is <a href=\"http://www.google.com\">google$</a>

If Line1 in the method- quoteReplacement is commented then I get java.lang.IllegalArgumentException: Illegal group reference at java.util.regex.Matcher.appendReplacement(Matcher.java:724)

If I leave it, the exception goes away but the string returned is

Plain text having \$. Anchor tag to be rewritten is <a href="http://www.google.com" target="_blank">google$</a>

after richText is assigned, but before anchorTagPattern is created, what does richText look like for error inputs? also, what does rText look like for error inputs? — Sam I am says Reinstate Monica
– Sam I am says Reinstate Monica, Commented Mar 14, 2012 at 19:29

Joop Eggen · Accepted Answer · 2012-03-14 19:56:57Z

1

Matcher.quoteReplacement should not be called on rText. The first question mark in the pattern seems superfluous. Only rewriteTag may be the cause.

formattedAnchorTag = Matcher.quoteReplacement(formattedAnchorTag);
matcher.appendReplacement(result, formattedAnchorTag);

edited Mar 14, 2012 at 19:56

answered Mar 14, 2012 at 19:40

Joop Eggen

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1 Comment

Joop Eggen Over a year ago

That should not matter. The source text may contain $ without special significance.

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