Getting leading digits of a string using Google Guava

Question

Basically, I have some strings like

5 - Avenue Rd
9 - Bellamy
21 - Brimley
191 - Highway 27 Rocket

And so on. I'm looking for a way using Google Guava to return the beginning digits. From what I've researched:

• CharMatcher.DIGIT.retainFrom is nice but I want it to stop at the first non-digit character.
• CharMatcher.DIGIT.trimLeadingFrom is pretty much what I want, except that it returns the other part of the string where I want a string of digits instead.

Any ideas?

EDIT: added another example.

Expected output for the four examples above:

5
9
21
191

Answer 1

Not quite equivalent, but

CharMatcher.DIGIT.negate().trimTrailingFrom(string);

Or -- a bit more involved, but this will work with intermediate digits --

string.substring(0, CharMatcher.DIGIT.negate().indexIn(string));

Or, with regexes, albeit with all the overhead that implies --

string.replaceAll("^(\\d+).*$", "$1")

Answer 2

Why don't you just split() the string on the "-" sign and then trim() and parse...

String test ="5 - Avenue Rd";
String[] out = test.split("-");
System.out.println(out[0].trim());

We don't need a framework to do that.