急需，我是初学Java的菜鸟，大家帮忙看一下下面这个有关集合的问题（打印每个字母出现的次数），怎么运行后没结果出现？？

public class Demo01{
    public static void main(String[] args){
        String[] str={"a","b","x","c","v","a","s"};
        TreeMap<String, Integer> tm=new TreeMap<String,Integer>();
        Set<Map.Entry<String , Integer>> set=tm.entrySet();
        Iterator<Map.Entry<String ,Integer>> iterator=set.iterator();
        for (int i = 0; i < str.length; i++) {
            
            if(!(tm.containsKey(str[i]))){
                tm.put(str[i],1);
            }else{
                Integer value=tm.get(str[i]);
                tm.put(str[i], value++);
               
            }
        
        }
        while(iterator.hasNext()){
            Map.Entry<String, Integer> me=iterator.next();
            String name=me.getKey();
            Integer time =me.getValue();
            System.out.println(name+(time));
            
        }
        
        
    }

}