Question

I need to match the following string with regular expressions in Java:

Hello: ${firstName} ${lastName}

And get this:

${firstName}

${lastName}

I tried this:

@Test
    public void testRegexMatch() {
        String regex = Pattern.quote("${") + ".+" + Pattern.quote("}");
        String str = "Hello: ${firstName} ${lastName}";
        Matcher m = Pattern.compile(regex).matcher(str);
        while (m.find()) {
            System.out.println(str.substring(m.start(), m.end()));
        }
    }

But I got the following output:

${firstName} ${lastName}

Answer 1

try replacing .+ with [^\}]+. which will match as many non-} characters as it can.

It is also important to note that this method is superior to using the non-greedy quantifier .+? because this will match without any backtracking, while the non-greedy version will backtrack once per character within the brackets. In this case, you will probably not notice a performance hit, but it is important to be in the habit of writing the most efficient regular expressions possible