Replace string with part of the matching regex

Question

I have a long string. I want to replace all the matches with part of the matching regex (group).

For example:

String = "This is a great day, is it not? If there is something, THIS IS it. <b>is</b>".

I want to replace all the words "is" by, let's say, "<h1>is</h1>". The case should remain the same as original. So the final string I want is:

This <h1>is</h1> a great day, <h1>is</h1> it not? If there <h1>is</h1> something, 
THIS <h1>IS</h1> it. <b><h1>is</h1></b>.

The regex I was trying:

Pattern pattern = Pattern.compile("[.>, ](is)[.<, ]", Pattern.CASE_INSENSITIVE);

Answer 1

Like this:

str = str.replaceAll(yourRegex, "<h1>$1</h1>");

The $1 refers to the text captured by group #1 in your regex.