Keyboard Row

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

Example 1:

Input: ["Hello", "Alaska", "Dad", "Peace"]
Output: ["Alaska", "Dad"]

Note:

1. You may use one character in the keyboard more than once.
2. You may assume the input string will only contain letters of alphabet.

public String[] findWords(String[] words) {
        if(words == null || words.length == 0){
            return words;
        }
        char [][]chars = {
                {'Q', 'q','W', 'w', 'E', 'e', 'R', 'r', 'T', 't', 'Y', 'y', 'U', 'u', 'I', 'i', 'O', 'o', 'P', 'p'},
                {'A', 'a', 'S', 's', 'D', 'd', 'F', 'f', 'G', 'g', 'H', 'h', 'J', 'j', 'K', 'k', 'L', 'l' },
                {'Z', 'z', 'X', 'x', 'C', 'c', 'V', 'v', 'B', 'b', 'N', 'n', 'M', 'm'}
        };
        int[] c2Line = new int[58];
        for(int i = 0; i < chars.length; i++){
            for(int j = 0; j < chars[i].length; j++){
                c2Line[chars[i][j] - 65] = i;
            }
        }
        List<String> result = new ArrayList<String>();
        for(String word : words){
            boolean isCan = true;
            for(int i = 1; i < word.length(); i++){
                if(c2Line[word.charAt(0) - 65] != c2Line[word.charAt(i) - 65]){
                    isCan = false;
                    break;
                } //if
            } //for
            if(isCan){
                result.add(word);
            }
        } //for
        String[] resultWords = result.toArray(new String[result.size()]);
        return resultWords;
    }