java 实现统计字母个数，并输出最多的字母

import java.util.HashMap;import java.util.Set;import java.util.Map;public class Test {    public static void main(String args[]) {        Map<Character, Integer> map = new HashMap<>();        String str = "today is a special day";        for(int i = 0; i < str.length(); i++) {            if(map.containsKey(str.charAt(i)))                map.put(str.charAt(i), map.get(str.charAt(i))+1);            else                map.put(str.charAt(i), 1);        }        Set<Character> set = map.keySet();        int max1 = -0xf3f3f3f;        for(Character key : set)            if(Character.isAlphabetic(key)) {                max1 = Math.max(map.get(key), max1);            }        System.out.println(max1);    }}