javaregex

Java regular expression and escaping meta characters


I am trying to write regexp for matching token embedded between two curly braces. For example if buffer Hello {World}, I want to get "World" token out of String. When I use regexp like \{*\} eclipse shows a error messages as

Invalid escape sequence (valid ones are \b \t \n \f \r \" \' \\)

Can anyone please help me? I am new to using regular expressions.


Solution

  • You should be able to extract the token from a string such as "{token}" by using a regexp of {(\w*)}. The parentheses () form a capturing group around the zero or more word characters captured by \w*. If the string matches, extract the actual token from the capturing group by calling the group() method on the Matcher class.

    Pattern p = Pattern.compile("\\{(\\w*)\\}");
    
    Matcher m = p.matcher("{some_interesting_token}");
    
    String token = null;
    if (m.matches()) {
     token = m.group();
    }
    

    Note that token may be an empty string because regex {\w*}" will match "{}". If you want to match on at least one token characters, use {\w+} instead.