Shortest word in Dictionary

有一个输入字符，然后我有一个英文字典，说白了就是字符串数组，然后写一个function返回字典里拥有输入字符串里所有字母(非数字或者空格等符号，就是纯字母)的最短的那个字符串。举个例子：
输入字符串”SR 456 T”，字符串数组里有”SORT”，而且是最短的，那么就返回它

public class ShortestDict {

	private List<String> wordList;
	private List<Integer> maskList;

	public ShortestDict(String[] words) {
		wordList = new ArrayList<String>();
		maskList = new ArrayList<Integer>();
		//rewrite comparator to compare string length
		Arrays.sort(words, new Comparator<String>(){
			public int compare(String s1, String s2) {
				return s1.length() - s2.length();
			}
		});

		for (String word : words) {
			wordList.add(word);
			maskList.add(getMask(word));
		}
	}

	public String getShortest(String inputWord) {
		int inputMask = getMask(inputWord);
		for (int i = 0; i < maskList.size(); i++) {
			if (inputMask == (inputMask & maskList.get(i))) {
				return wordList.get(i);
			}
		}
		return "";
	}

	public static int getMask(String word) { 
		int mask = 0;
		word = word.toLowerCase();
		for (char c : word.toCharArray()) {
			if ('a' <= c && c <= 'z') {
				mask |= (1 << (c - 'a'));
			} 
		}
		return mask;
	}

	public static void main(String[] args) {
		String[] words = new String[]{"so99ort", "so1rt", "skype", "so11rt", "apppples"};
		ShortestDict d = new ShortestDict(words);
		System.out.println(d.getShortest("SR 456 T"));

	} 
}