Reading contents inside brackets in Java?

Question

I'm trying to read in some information from a file in Java, and the file contents are formatted like this:

InitialState [+A(B),+C(D)]
GoalState [-A(B),+C(D),-E(F)]

I'm trying to loop through the file and grab only the contents inside the brackets, so the arrays I create should look like this:

initial = ['+A(B)', '+C(D)']
goal = ['-A(B)', '+C(D)', '-E(F)']

Should I use a regex to do this? So far, I have

if (line.charAt(0) == 'I') {
  String[] initialStateString = (line.subString(line.subString(13, line.length() - 1)).split(","));
  for (String s: initialStateString) {
    initialState.add(s);
  }
}

if (line.charAt(0) == 'G') {
  String[] goalStateString = (line.subString(line.subString(11, line.length() - 1)).split(","));
    for (String s: goalStateString) {
      goalState.add(s)''
    }
}

This basically starts the index of the substring to be right after the bracket I believe, but I would like to use something that just takes the contents of the bracket as I believe that will be more robust. Thank you.

Answer 1

try this code :

public static void main(String[] args) {
    String s = "InitialState [+A(B),+C(D)]";
    String s1 ="GoalState [-A(B),+C(D),-E(F)]";

    Pattern p = Pattern.compile("([+-]\\w\\(\\w\\))");

    Matcher m = p.matcher(s);
    while(m.find()){
        System.out.print(m.group(1)+"  ");
    }

    System.out.println();

    m = p.matcher(s1);
    while(m.find()){
        System.out.print(m.group(1)+"  ");
    }
}

output :

+A(B)  +C(D)  
-A(B)  +C(D)  -E(F)

explanation for regex :

[+-] : Match "+" or "-" character.
\\w  : Match any word character.
\\( : Match "(".
\\) : Match ")"