怎么在一串长字符串中找出出现最多次数的字符?

import java.util.*;
public class CountMax {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String s = "hidjahgugahjjaiosdhgbh";
        char[] chs = s.toCharArray();
        HashMap<Character,Integer> myMap = new HashMap<Character,Integer> ();
        for(char ch : chs)
            if ( myMap.containsKey(ch))
            {
                myMap.put(ch, (myMap.get(ch) +1));
            }
            else
                myMap.put(ch,1);
         System.out.println(myMap);
        //遍历一便，找出最大值
        Integer maxValue =new Integer(0);
        Character maxKey = new Character('a');

        Set<Character> keys = myMap.keySet();
        for(Iterator<Character> it =keys.iterator();it.hasNext();)
        {   
            Character key = it.next();
            Integer value = myMap.get(key);
            if(value > maxValue)
            {
                maxKey=key;
                maxValue=value;
            }
        }
        System.out.println("max entry: " + maxKey + "..."+maxValue);
    }
}