Java统计字符串中每个字符出现次数

要求：输入一个字符串，统计字符串中每个字符出现的次数

import java.util.HashMap;
import java.util.Scanner;
import java.util.Set;
public class Demo {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入需要检测的字符串：");
        String s = sc.nextLine();
        HashMap hm = new HashMap();
        for(int i=0;i keySet = hm.keySet();
        for(Character key:keySet){
            Integer value = hm.get(key);
            System.out.println(key +","+value);
        }
    }
}

运行结果