I am new to regex and am having trouble making this work. The following line returns false but I think it should return true.
Pattern.matches("^DOI", "DOI 10.1364/OL.36.002946")
What I want is to match the first three letters "DOI", regardless of what comes after it. I try to remove the anchor but it still does not match. Can anyone help explain it for me?
Just use
String yourVar = "DOI dskljdj";
if (yourVar.startsWith("DOI")) { ... }
It will check if your String begins with DOI or not.
You can try with
System.out.println(Pattern.matches("^DOI.*", "DOI 10.1364/OL.36.002946"));
You want your text to start with DOI and after that you just want any amount of any character .*
However as stated in the other responses, String.startWith is way better if you are only checking that your string starts with a fixed prefix. Regexp will allow you to do more powerful things though, however it is more painful performance wise (and way more complex code wise).
This is the best route to go
String.startsWith("DOI");
