Question

I have a string like that: obj[attr1=val1 attr2=val2 attr3=val3]
i need to extract object name and attributes.

Earlier, i’ve decided similar task in javascript using next regexp:

/^(\w+)(?:\[(\w+=\w+)(?:\s(\w+=\w+))*\])?$/

Now i have a trouble deciding in java:

Pattern pathPattern = Pattern.compile("^(\\w+)(?:\\[(\\w+=\\w+)(?:\\s+(\\w+=\\w+))*\\])?$");

I’m getting just a object name and first attribute.
It seems that Mather class gets group count corresponding to count of “()” without considering symbol “*”.

Is exists the possibility to make working java reg exp like js regexp, or i need to make two steps extraction?

thank you

Answer 1

Matcher.groupCount() only counts the number of opening-brackets and consider them to be a group. So, the number of brackets you open will be the number of group counts (provided you are not using any non-capturing group).

You can use the below pattern to get the value inside the [.*]: –

Pattern pattern = Pattern.compile("(?:\\b)(\\w+?)=(\\w+?)(?:\\b)");
Matcher matcher = pattern.matcher(str);

while (matcher.find()) {
    System.out.println(matcher.group(1) + " : " + matcher.group(2));
}

This will match all the attr=val pair inside the [ and ].

OUTPUT: –

attr1 : val1
attr2 : val2
attr3 : val3

UPDATE: –

Since you don’t have to do a boundary check in your above string, the above pattern can even be simplified to: –

Pattern pattern = Pattern.compile("(\\w+?)=(\\w+)");