Java Regex in round brackets

Question

I am trying to parse an input string like this

String input = "((1,2,3),(3,4,5),(2,3,4),...)"

with the aim of getting an array of String where each element is an inner set of integers i.e.

array[0] = (1,2,3)
array[1] = (3,4,5)

etc.

To this end I am first of all getting the inner sequence with this regex:

String inner = input.replaceAll("\\((.*)\\)","$1");

and it works. Now I'd like to get the sets and I am trying this

String sets = inner.replaceAll("((\\((.*)\\),?)+","$1")

But I can't get the result I expected. What am I doing wrong?

Rohit Jain · Accepted Answer · 2014-03-22 07:50:55Z

3

Don't use replaceAll to remove the parentheses at the ends. Rather use String#substring(). And then to get the individual elements, again rather than using replaceAll, you should use String#split().

String input = "((1,2,3),(3,4,5),(2,3,4))";
input = input.substring(1, input.length() - 1);

// split on commas followed by "(" and preceded by ")"
String[] array = input.split("(?<=\\)),(?=\\()");

System.out.println(Arrays.toString(array));

answered Mar 22, 2014 at 7:50

Rohit Jain

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1 Comment

Rohit Jain Over a year ago

@lowcoupling Those are look-behind and look-ahead respectively.

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