Regular expression to check for string between special characters in java

Question

I have to check if the string provided has a specific format. The format is as follows: "This is just an #<example string> just for test. This string has to be of this #<specific format> ".

If you look at the string, it has special characters #<> with some string in between #< and > . I tried with regular expression: Pattern.compile("^[#<a-zA-Z0-9>]*$").matcher(string).find() but it returns true even if I don't provide the special characters at the beginning or at the end.

I tried with an if condition too: if(string.matcher("#<")) but I think this approach is lame. I'd rather go with the regular expresson.

What am I doing wrong here?

Answer 1

To match 1 or more "words" using the chars a-zA-Z0-9 between #<...> and a whitespace boundary on the left and right, you could use

(?<!\S)#<[a-zA-Z0-9]+(?: [a-zA-Z0-9]+)*>(?!\S)

In Java

String regex = "(?<!\\S)#<[a-zA-Z0-9]+(?: [a-zA-Z0-9]+)*>(?!\\S)";

Regex demo

Answer 2

Try: Pattern.compile("#<(.*?)>")

Suggest you use a website like https://regex101.com/ to help you build these.