计算一个字符串种每个字符出现的次数

String str ="2342asfghgyu56asdasda";
Map<String,Integer> maps = new HashMap<String,Integer>();
for(int i=0;i<str.length();i++){
    String key = String.valueOf((str.charAt(i)));
    if(!maps.containsKey(key))
        maps.put(key, 1);
    else{
         int val =maps.get(key);
        maps.put(key, val+1);
    }
}

for(Map.Entry i : maps.entrySet()){
    System.out.println(i.getKey()+ "=="+i.getValue());
}