不用字符数组也可以,看个人
String sc = "jfvckuycvyufuyfv";
HashMap<Character, Integer> hashMap = new HashMap<>();
Set<Character> keySet = hashMap.keySet();
char[] chars=sc.toCharArray();
for(int i=0;i<chars.length;i++){
Integer value = hashMap.get(chars[i]);
if(value==null){
hashMap.put(chars[i],1);
}else {
value++;
hashMap.put(chars[i],value);
}
}
for (Character key:keySet){
Integer value = hashMap.get(key);
System.out.println(key+","+value);
}