Bits and bites from Pål Brattberg

Here’s a little method I had to write yesterday to split a CamelCase’d word into a string separated by spaces instead (as a part of my Java-based Wiki Bot software).

No frills, just accepts a String such as "CamelCase" and returns "Camel Case". The code uses Java’s regular expressions to split the string on \p{Lu}, which is just regex fancy speak for any unicode upper case letter.

Enjoy.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
 * Simple test case for splitting a CamelCase word.
 *
 * @author Pål Brattberg
 */
public class Test {
    /**
     * Split a CamelCase string into a space separated string.
     *
     * @param inputString
     *            The string you wish to split.
     * @return A string where each upper case letter is separated by a single
     *         space
     */
    public static String unCamelize(final String inputString) {
        Pattern p = Pattern.compile("\\p{Lu}");
        Matcher m = p.matcher(inputString);
        StringBuffer sb = new StringBuffer();
        while (m.find()) {
            m.appendReplacement(sb, " " + m.group());
        }
        m.appendTail(sb);
        return sb.toString().trim();
    }

    public static void main(String[] args) {
        String s = "CamelCase";
        System.out.printf("%s -> %s", s, unCamelize(s));
    }
}

The program outputs “CamelCase -> Camel Case”.

Go to Sun for more on Java regex.