获取字符串中出现最多的字符 （HashMap()储存）

import java.util.HashMap;
import java.util.Map;

public class number_of_character {

public static void main(String[] args) {
// TODO Auto-generated method stub
String s = "asdasdugahjjaiosdhgbh";
Map <Character, Integer> map = new <Character, Integer> HashMap();
int len = s.length();


for(int i=0; i<s.length();i++) {
Character k = s.charAt(i);
map.put(k, (map.get(k) == null ? 1: map.get(k) + 1));
}

System.out.println(map);

char key = 0;
int min=-1;
for (Map.Entry<Character, Integer> entry : map.entrySet()) {
if(min<entry.getValue())
{
min=entry.getValue();
key=entry.getKey();
}

}
System.out.println("Key = " + key + ", Value = " +min);
}

}