RegEx replacement

Question

I'm trying to make a small parsing engine that does the following:
1. reads an HTML document
2. searches for special tags of the form [key]
3. looks up the key in a hashmap or something
4. replaces [key] with value from the hashmap
I'm storing the HTML document line by line as strings in an ArrayList (any better way to do this?). I iterate through each line, replacing each tag with its corresponding value. The thing is, however, that I'd like to use RegEx as much as possible.
The java.lang.String.matches(String regex) method tells me, through a boolean return value, whether the current line actually contains any tag at all , while the java.lang.String.replaceFirst(String regex, String replacement) method solves the replacement part. What the String class methods don't provide me with is a method for returning the actual substring that was found during the java.lang.String.matches(String regex) call. Is there any such method out there? Right now I'm doing this manually, using the String class' indexOf(...) and lastIndexOf(..) methods.
In short, what I'm looking for is a method something like String find(String text, String regex) that would return "salary" when called as find("<h1>[salary]</h1>", ".*\\[.*\\].*")
Thanks for your help!

Answer 1

You must use Patterns and Matchers (java.util.regex.*).
In short, what I'm looking for is a method something like String find(String text, String >regex) that would return "salary" when called as find("<h1>[salary]</h1>", ".*\\[.*\\].*")Let's
String html
be your input.
Pattern p = Pattern.compile("(?im)<h1>(.*?)</h1>");
Matcher m = p.matcher(html);
if( m.find() ){
// the whole matching substring is in m.group();
// the string within the h1's is in m.group(1)
}