Java Regex Replace with Capturing Group

user_145359 0
Viewed 109714

Is there any way to replace a regexp with modified content of capture group?

Example:

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher(text);
resultString = regexMatcher.replaceAll("$1"); // *3 ??

And I'd like to replace all occurrence with $1 multiplied by 3.

edit:

Looks like, something's wrong :(

If I use

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher("12 54 1 65");
try {
    String resultString = regexMatcher.replaceAll(regexMatcher.group(1));
} catch (Exception e) {
    e.printStackTrace();
}

It throws an IllegalStateException: No match found

But

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher("12 54 1 65");
try {
    String resultString = regexMatcher.replaceAll("$1");
} catch (Exception e) {
    e.printStackTrace();
}

works fine, but I can't change the $1 :(

edit:

Now, it's working :)

regex java
4 Answers

Java 9 offers a Matcher.replaceAll() that accepts a replacement function:

resultString = regexMatcher.replaceAll(
        m -> String.valueOf(Integer.parseInt(m.group()) * 3));
user_15538510
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