Regular Expression Pattern to Match Words in All Caps That Are Followed By a colon

Question

I need a pattern to match words like APPLE: or PEAR:

[A-Z][:] will match the R: but not the whole word and thus gives me a false when I try to match.

Can anybody help?

Answer 1

You want to match one or more capital letter which means you need to use a +. Also your : doesn't need to be in a character class:

[A-Z]+:

Answer 2

Just add a "quantifier":

/[A-Z]+:/

Note you don't need a character class for a single character.

Answer 3

How about \b[A-Z]+:? The \b is for checking a word boundary btw.

Answer 4

\b can be used to capture characters only in a word-boundary ie between the start and end of a word.

[A-Z] indicates a range of characters and specifying A-Z specifically matches the range of characters from capital A to capital Z. In other words, only upper case letters.

End the query by trying to match a semicolon and you'll find matches of a capital letter word immediately followed by a single semi-colon.

You can use the regular expression in Java like below.

import java.util.regex.*;

public class RegexExample {
  System.out.println(
    Pattern.matches("\b[A-Z]+:", "data: stuff, MIX!: of, APPLE: or, PEAR: or, PineAPPLes: yay!")
  );
}

I recommend finding an online playground for regular expressions. Iterating and experimenting with regexes for a project can be a fast way to learn the limitations and find ways to simplify or improve an expression.