import java.util.*;
import java.lang.*;
import java.util.Map.Entry;
public class Main{
public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();  
        char[] arr = s.toCharArray();  
        HashMap<Character, Integer> map = new HashMap<>();  
        for (char c : arr) {  
            map.put(c, !map.containsKey(c) ? 1 : (map.get(c) + 1));  
        }    
        for (Character key : map.keySet()) {  
            System.out.println(key + "=" + map.get(key));  
        }  
        Set<Entry<Character,Integer>> sets = map.entrySet();      //獲取HashMap鍵值對(duì)    
    for(Entry<Character,Integer> set:sets){             //遍歷HashMap鍵值對(duì)  
        System.out.println("Key:"+set.getKey()+"    value:"+set.getValue());  
    }  
        sc.close();
    }
}

參考http://blog.csdn.net/fishroad/article/details/47421457