//hashMap的遍歷方式1
		Iterator<Entry<Character, Integer>> iter = map.entrySet().iterator();
                char ch;
		while(iter.hasNext()){
			Map.Entry<Character, Integer> entry = (Map.Entry<Character, Integer>) iter.next();
			if(entry.getValue()==1) {
				ch = entry.getKey();
				return ch;
			}			
		}
 

                //方式2
		 for(Map.Entry<Character, Integer> entry:map.entrySet()){
			if(entry.getValue()==1)return entry.getKey();
		}