面试题目字符统计

import java.util.HashMap;
import java.util.Map;


public class firstNonRepeatedChar  {

    public static void main(String args[]) {
        String s = "tbbbotoal";
        Map map = new HashMap();        
        char[] charArgs = s.toCharArray();
        char flag = ' ';
        for(char c : charArgs){
            
            if(!map.containsKey(c) && flag != c){
                map.put(c, "value");
            } else {
                map.remove(c);
                flag = c;
            }
        }
        
        System.out.println(map.keySet().toArray()[0]);
    }
}

输出：a