题解 | #字符串排序#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        List<Character> al = new ArrayList<>(); 
        StringBuilder sb = new StringBuilder();
        while (in.hasNext()) { 
            String s = in.nextLine();
            for(int i = 0; i<s.length(); i++){
                if(Character.isLetter(s.charAt(i))){
                    al.add(s.charAt(i));
                }
            }
            al.sort(new Comparator<Character>(){
                public int compare(Character o1,Character o2){
                    return Character.toLowerCase(o1) - Character.toLowerCase(o2);
                }
            });
            for(Character c : al){
                sb.append(c);
            }
            for(int i = 0; i<s.length(); i++){
                if(!Character.isLetter(s.charAt(i))){
                    sb.insert(i,s.charAt(i));
                }
            }
            System.out.print(sb);
        }
    }
}