题解 | 字符串排序

import java.util.Scanner;

import java.util.*;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str=in.nextLine();
        char[] chs=str.toCharArray();
        List<Character> letters=new ArrayList<>();
        for(int i=0;i<chs.length;i++){
             if(Character.isLetter(chs[i]))
              letters.add(chs[i]);
        }
      letters.sort(new Comparator<Character>(){
            public int compare(Character o1,Character o2){
                return Character.toLowerCase(o1)-Character.toLowerCase(o2);
            }
      });


      StringBuilder result=new StringBuilder();
      for(int i=0,j=0;i<str.length();i++){
        if(Character.isLetter(str.charAt(i))){
            result.append(letters.get(j));
            j++;
        }else{
            result.append(str.charAt(i));
        }

      }
      System.out.println( result.toString());


    }
}