How can I obtain what .* matched in a regular expression?

Question

I have thousands of different regular expressions and they look like this: ``` ^Mozilla.*Android.*AppleWebKit.*Chrome.*OPR\/([0-9\.]+) ``` How do I obtain those substrings that match the `.*` in the regex? For example, for the above regex, I would get four substrings for four different `.*`s. In addition, I don't know in advance how many `.*`s there are, even though I can possibly find out by doing some simple operation on the given regex string, but that would impose more complexity on the program. I process a fairly big amount of data, so really focus on the efficiency here.

Accepted Answer

Replace the `.*`s with `(.*)`s and use `matcher.group(n)`. For instance:

```
Pattern p = Pattern.compile("1(.*)2(.*)3");
Matcher m = p.matcher("1abc2xyz3");
m.find();

System.out.println(m.group(2));
```

```
xyz
```

Notice how the match of the second `(.*)` was returned (since `m.group(2)` was used).

Also, since you mentioned you won't know how many `.*`s your regex will contain, there is a `matcher.groupCount()` method you can use, if the only capturing groups in your regex will indeed be `(.*)`s.

For your own enlightenment, try reading about capturing groups.

How can I obtain what .* matched in a regular expression?

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