Java regex to obtain value between parenthesis

Question

Regular expression to obtain value from [[text]]. I have tried the regex

  "((?<=[[)*(?=]])*)+"  the value between [[ ]] is not obtained.

For example, from the string [[text]], we should obtain text.

Pattern pat = Pattern.compile("((?<=\\[[)*(?=\\]])*)");
Matcher matcher = pat.matcher("[[text]]");
String next ="";
while(matcher.find()) {
  next = matcher.group(0);
break;
}
System.out.println(next); //next should be text

Answer 1

You need to escape brackets [] when using them as actual characters in a regular expression. And you also need to add something to actually capture what is between the brackets. You can use .* for that or use my approach, if you are sure the value cannot contain a ] .

((?<=\[\[)([^\]]*)(?=\]\]))+

There is not even really a need to use lookbacks und lookaheads unless you explictly need to exempt those limiters from the match. This will work just as well:

 \[\[([\]]*\]\]

And obviously when you put these into a String, you need to add additional \\ to escape the \\ for the String...they are just more readable this way.

Answer 2

如果您不想使用regex ， String.replaceAll也可以为您提供帮助。

String s2 = s.replaceAll("\\[", "").replaceAll("\\]", "");

Answer 3

"(?<=\\[\\[)[^\\]]*"

这应该为你工作