Question

I’ve got the following code:

public class testMatch {

    public static void main(String[] args) {
        String dummyMessage = "asdfasdfsadfsadfasdf 3 sdfasdfasdfasdf";
        String expression = "3";
        if (dummyMessage.matches(expression)){
            System.out.println("MATCH!");
        } else {
            System.out.println("NO MATCH!");
        }

    }
}

I’d expect this to be a successful match as the dummyMessage contains the expression 3 but when I run this snippet the code prints NO MATCH!

I don’t get what I’m doing wrong.

OKAY STOP ANSWERING! .*3.* works
This is an over simplification of an issue I have in some live code, the regex is configurable, and up until now matching the entire string has been okay, I’ve now had to match a part of the string and was wondering why it wasn’t working.

Answer 1

It matches against the whole string, i.e. like ^3$ in most other regex implementations. So 3 does not match e.g. 333 or your string. But .*3.* would do the job.

However, if you just want to test if “3” is contained in your string you don’t need a regex at all. Use dummyMessage.contains(expression) instead.