Java Regex for custom function

Question

I'm looking for a Regex pattern that matches the following, but I'm kind of stumped so far. I'm not sure how to grab the results of the two groups I want, marked by id, and attr.

Should match:

account[id].attr
account[anotherid].anotherattr

These should respectively return id, attr,
and anotherid, anotherattr

Any tips?

Can we see your attempts to solve this task? How do you think regex which can match account[xxx].yyy may look like? — Pshemo
– Pshemo, Commented Sep 4, 2014 at 15:59
I guess I just want to match account[sometext].moretext and grab the sometext and moretext fields. It seems possible! — phouse512
– phouse512, Commented Sep 4, 2014 at 16:18

Mena · Accepted Answer · 2014-09-04 16:08:56Z

2

Here's a complete solution mapping your id -> attributes:

String[] input = {
        "account[id].attr",
        "account[anotherid].anotherattr"
};
//                           | literal for "account"
//                           |      | escaped "["
//                           |      |  | group 1: any character 
//                           |      |  |   | escaped "]"
//                           |      |  |   |  | escaped "."
//                           |      |  |   |  |  | group 2: any character
Pattern p = Pattern.compile("account\\[(.+)\\]\\.(.+)");
Map<String, String> output = new LinkedHashMap<String, String>();
// iterating over input Strings
for (String s: input) {
    // matching
    Matcher m = p.matcher(s);
    // finding only once per input String. Change to a while-loop if multiple instances
    // within single input
    if (m.find()) {
        // back-referencing group 1 and 2 as key -> value
        output.put(m.group(1), m.group(2));
    }
}
System.out.println(output);

Output

{id=attr, anotherid=anotherattr}

Note

In this implementation, "incomplete" inputs such as "account[anotherid]." will not be put in the Map as they don't match the Pattern at all.

In order to have these cases put as id -> null, you only need to add a ? at the end of the Pattern.

That will make the last group optional.

edited Sep 4, 2014 at 16:08

answered Sep 4, 2014 at 16:03

Mena

48.6k11 gold badges90 silver badges110 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

phouse512 Over a year ago

hmm snag.gy/ZHHzk.jpg shows that it doesn't match... otherwise looks good!!

Mena Over a year ago

@phouse512 Quoth the server, 404. Although testing your Java Patterns with Java has the clear advantage over web tools of actually seeing it matched with the Java regex engine.

Mena Over a year ago

@phouse512 same answer (minus the 404): probably a different engine, or different way to handle escapes (i.e. single vs double).

Collectives™ on Stack Overflow

Java Regex for custom function

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related