Replace String in Java with regex and replaceAll

Question

Is there a simple solution to parse a String by using regex in Java?

I have to adapt a HTML page. Therefore I have to parse several strings, e.g.:

href="/browse/PJBUGS-911"
=>
href="PJBUGS-911.html"

The pattern of the strings is only different corresponding to the ID (e.g. 911). My first idea looks like this:

String input = "";
String output = input.replaceAll("href=\"/browse/PJBUGS\\-[0-9]*\"", "href=\"PJBUGS-???.html\"");

I want to replace everything except the ID. How can I do this?

Would be nice if someone can help me :)

Martin Ender · Accepted Answer · 2012-12-03 19:02:54Z

3

You can capture substrings that were matched by your pattern, using parentheses. And then you can use the captured things in the replacement with $n where n is the number of the set of parentheses (counting opening parentheses from left to right). For your example:

String output = input.replaceAll("href=\"/browse/PJBUGS-([0-9]*)\"", "href=\"PJBUGS-$1.html\"");

Or if you want:

String output = input.replaceAll("href=\"/browse/(PJBUGS-[0-9]*)\"", "href=\"$1.html\"");

answered Dec 3, 2012 at 19:02

Martin Ender

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1 Comment

erwingun2010 Over a year ago

Thank you for your very quick answer and solution. Works fine :-)

Rohit Jain · Accepted Answer · 2012-12-03 19:08:35Z

1

This does not use regexp. But maybe it still solves your problem.

output = "href=\"" + input.substring(input.lastIndexOf("/")) + ".html\"";

edited Dec 3, 2012 at 19:08

Rohit Jain

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answered Dec 3, 2012 at 19:05

bert

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5 Comments

ean5533 Over a year ago

Don't forget to add ".html" to the end

Rohit Jain Over a year ago

Pretty simple and straightforward this is.

ean5533 Over a year ago

@Vulcan Yes there is. He requires it for his answer.

Martin Ender Over a year ago

I believe input is not a single href="/browse/..." but a whole HTML file. Hence, the explicit mentioning of replaceAll in the question.

bert Over a year ago

Thanks for the edit. And yes you're probably right @m.buettner

amphibient · Accepted Answer · 2012-12-03 19:29:57Z

This is how I would do it:

public static void main(String[] args) 
    {
        String text = "href=\"/browse/PJBUGS-911\" blahblah href=\"/browse/PJBUGS-111\" " +
                "blahblah href=\"/browse/PJBUGS-34234\"";

        Pattern ptrn = Pattern.compile("href=\"/browse/(PJBUGS-[0-9]+?)\"");

        Matcher mtchr = ptrn.matcher(text);

        while(mtchr.find())
        {
            String match = mtchr.group(0);
            String insMatch = mtchr.group(1);



            String repl = match.replaceFirst(match, "href=\"" + insMatch + ".html\"");

            System.out.println("orig = <" + match + "> repl = <" + repl + ">");
        }
    }

This just shows the regex and replacements, not the final formatted text, which you can get by using Matcher.replaceAll:

String allRepl = mtchr.replaceAll("href=\"$1.html\"");

If just interested in replacing all, you don't need the loop -- I used it just for debugging/showing how regex does business.

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