Pattern to extract text between parenthesis

List<String> matchList = new ArrayList<String>();
Pattern regex = Pattern.compile("\\((.*?)\\)");
Matcher regexMatcher = regex.matcher("Hello This is (Java) Not (.NET)");

while (regexMatcher.find()) {//Finds Matching Pattern in String
   matchList.add(regexMatcher.group(1));//Fetching Group from String
}

for(String str:matchList) {
   System.out.println(str);
}

OUTPUT

Java
.NET

---

What does \\((.+?)\\) mean?

This regular Expression pattern will start from \\( which will match ( as it is reserved in regExp so we need escape this character,same thing for \\) and (.*?) will match any character zero or more time anything moreover in () considered as Group which we are finding.

Try this:

String x = "Hello (Java)";
Matcher m = Pattern.compile("\\((.*?)\\)").matcher(x);
while (m.find()) {
    System.out.println(m.group(1));
}

or

String str = "Hello (Java)";
String answer = str.substring(str.indexOf("(")+1, str.indexOf(")"));

there is something even simpler than using regex:

String result = StringUtils.substringBetween(str, "(", ")");

In your example, result would be returned as "Java". I would recommend the StringUtils library for various kinds of (relatively simple) string manipulation; it handles things like null inputs automatically, which can be convenient.

Documentation for substringBetween(): https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html#substringBetween-java.lang.String-java.lang.String-java.lang.String-

There are two other versions of this function, depending on whether the opening and closing delimiters are the same, and whether the delimiter(s) occur(s) in the target string multiple times.