Regular expression for special character $

Question

I have a string "any tag$@ws2-role$@ws1-role" and I want to have a regular expression to search a word starting with "$@" and ending either with "$@" or with end of a line.

For example, for the above input, the output has to be ws2-role and ws1-role.

I tried below regular expression but I am not able to figure out how to add or operator for pattern2 so that it can also consider end of line for giving the output eg $@|$. $@ is the exact word to be match and $ to look until the end of line.

String pattern1 = "$@";
String pattern2 = "$@";
Pattern pattern = Pattern.compile(Pattern.quote(pattern1) + "(.*?)" + Pattern.quote(pattern2));
    Matcher matcher = pattern.matcher(tag);
    // check all occurance
    while (matcher.find()) {
      System.out.println(matcher.group());
    }

Can anyone gives some hints?

Many Thanks in Advance

Answer 1

Try this

Pattern pattern = Pattern.compile("\\$@([^\\$@]+|$)");
CharSequence tag = "any tag$@ws2-role$@ws1-role";
Matcher matcher = pattern.matcher(tag);
while (matcher.find()) {
    System.out.println(matcher.group(1));
}

Output

ws2-role
ws1-role

Answer 2

您可以为此使用基于前瞻的正则表达式：

String regex = "\\$@\\S+(?=\\$@|$)";