LeetCode500. Keyboard Row(ArrayL

public class Solution {
    public String[] findWords(String[] words) {
        String regex="[qwertyuiop]*|[asdfghjkl]*|[zxcvbnm]*";
        String a;
        ArrayList<String> list = new ArrayList<>();
        for(int i=0;i<words.length;i++){
            a = words[i].toLowerCase(); 
            if(a.matches(regex)) list.add(words[i]); 
        }
        return list.toArray(new String[0]);//若直接返回list报错，必须转化下
    }
}