Java Regex only start of string

Question

I have a huge string which I would like to match to the following regex:

"\\s*<?.*?>\\s*<abc>[\\s\\S]*|\\s*<abc>[\\s\\S]*"

as in

myHugeString.matches("\\s*<?.*?>\\s*<abc>[\\s\\S]*|\\s*<abc>[\\s\\S]*"));

The string is enormous, so matching the [\s\S]* at the end is taking up a huge amount of time. I am looking to only match the first portion (\\s*<?.*?>\\s*<abc>), and I don't care about anything after that.

What would be the most efficient way of going about this

Thanks

Paul Vargas · Accepted Answer · 2013-08-08 23:22:22Z

1

You can use Pattern and Matcher classes here:

Create a Pattern object by compiling the regex using Pattern#compile(regex).
Then create a Matcher object by applying that Pattern object on your string using Pattern#matcher(CharSequence).
And then use Matcher#find() method to find the pattern you are interested in.

Sample Code:

Pattern pattern = Pattern.compile("\\s*<?.*?>\\s*<abc>|\\s*<abc>");
Matcher matcher = pattern.matcher(yourString);

if (matcher.find()) {
    // Pattern found.
}

You can even shorten your regex pattern to:

"(?:\\s*<?.*?>)?\\s*<abc>"

edited Aug 8, 2013 at 23:22

Paul Vargas

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answered Aug 8, 2013 at 22:26

Rohit Jain

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