simple regex practice

SimpleRegexPractice.java

class RegexUtility {
	public static String[] matches(String pattern, String[] words) {
		String s = pattern;
		for (int i = 0; i < words.length; i++) {
			if (!(words[i].matches(pattern))) words[i] = null;
		}
		return words; 
	}
}

class RegexTester {
	public static void main(String... argsz) {
		String pattern = "([\\w])([\\D])\\1([\\w])([\\w])\\2";
		String[] words1 = new String[]{"9B99BB","ABABBB","abaAB","abaab","ABaab"};
		//printing out matches for given pattern and Strings
		StringBuilder bob = new StringBuilder(); 
		bob.append("Matches: "); 
		for (String s : RegexUtility.matches(pattern,words1)) {
			if (s != null) bob.append(s + ", "); 
		}
		bob.deleteCharAt(bob.length()-2); //remove trailling ','
		System.out.println(bob); 
	}
}