剑指offer-字符流中第一个不重复的字符

public class Solution {//map my
    //Insert one char from stringstream
    LinkedHashMap<Character,Integer> map = new LinkedHashMap<>();
    public void Insert(char ch)
    {
        if(map.containsKey(ch)){
            map.put(ch,map.get(ch)+1);
        }
        else{
            map.put(ch,1);
        }
    }
  //return the first appearence once char in current stringstream
    public char FirstAppearingOnce()
    {
        Iterator iter = map.entrySet().iterator();
        while(iter.hasNext()){
            Map.Entry entry = (Map.Entry) iter.next();
            if(1==(Integer) entry.getValue()){
                return (Character)entry.getKey();
            }
        }
        return ‘#‘;
    }
}