题解 | #字符串排序#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String line = scanner.nextLine();

        List<Character> characters = new ArrayList<>();

        char[] charArray = line.toCharArray();
        for (char ch : charArray) {
            if (Character.isLetter(ch)) {
                characters.add(ch);
            }
        }

        characters.sort(new Comparator<Character>() {
            @Override
            public int compare(Character o1, Character o2) {
                return Character.toLowerCase(o1) - Character.toLowerCase(o2);
            }
        });

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

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

}