输入字符串，打印统计各个字符的个数

public class Test {
    public static void main(String[] args) {
        Scanner Sc = new Scanner(System.in);
        System.out.println("请输入字符串：【按下回车结束输入】");
        String str = Sc.next();
        char[] chars = str.toCharArray();
        HashMap hm = new HashMap<>();
        for (char aChar : chars) {
            if (!hm.containsKey(aChar))
                hm.put(aChar, 1);
            else hm.put(aChar, hm.get(aChar) + 1);
        }
        for (Character key : hm.keySet()) {
            System.out.println(key + "在" + str + "中，有" + hm.get(key) + "个");
        }
    }
}

运行结果：