Regular expression masking in java

Question

So, I have an IP address as a string. I have this regular expression. (\d{1-3})\.(\d{1-3})\.(\d{1-3})\.(\d{1-3}) How do I print the relevant groups?

Thanks!

Answer 1

import java.util.regex.*;
try {
    Pattern regex = Pattern.compile("(\\d\\{1-3\\})\\.(\\d\\{1-3\\})\\.(\\d\\{1-3\\})\\.(\\d\\{1-3\\})");
    Matcher regexMatcher = regex.matcher(subjectString);
    while (regexMatcher.find()) {
        for (int i = 1; i <= regexMatcher.groupCount(); i++) {
            // matched text: regexMatcher.group(i)
            // match start: regexMatcher.start(i)
            // match end: regexMatcher.end(i)
        }
    } 
} catch (PatternSyntaxException ex) {
    // Syntax error in the regular expression
}

Answer 2

If you use Pattern and Matcher to execute your regular expression, you can query Matcher for each group using the int group method

So:

Pattern p = Pattern.compile("(\\d{1-3}).(\\d{1-3}).(\\d{1-3}).(\\d{1-3})"); 
Matcher m = p.matcher("127.0.0.1"); 
if (m.matches()) {   
  System.out.print(m.group(1));  
  // m.group(0) is the entire matched item, not the first group.
  // etc... 
}