java中字符串的问题

这个不难实现的，参考以下代码：
import java.util.*;
public class T {
public static void main(String[] args) {
String s = "abcdkdieakdfoealjdflsa";
Map<Character,Integer> map=count(s);
Set<Character> set = map.keySet();
int num = 0;
for(Character c : set){
System.out.println("字符" + c + "：共有" + map.get(c) + "个");
num ++;
}
System.out.println("该字符串中一共有" + num + "种字符");
}
public static Map<Character,Integer> count(String s){
char[] cs = s.toCharArray();
Map<Character,Integer> result = new HashMap<Character,Integer>();
for(char c : cs){
if(result.containsKey(c)){
int a = result.get(c)+1;
result.put(c, a);
continue;
}
result.put(c, 1);
}
return result;
}
}

public class test{
static void prt(String str){
StringBu