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);
        char[] chr = in.nextLine().toCharArray();
        List<String> list = new ArrayList<String>();
        for (char index : chr) {
            if (Character.isLetter(index)) {
                list.add(String.valueOf(index));
            }
        }
        Collections.sort(list, String.CASE_INSENSITIVE_ORDER);
        Iterator<String> it = list.iterator();
        for (char index : chr) {
            if (Character.isLetter(index)) {
                System.out.print(it.next());
            } else {
                System.out.print(index);
            }
        }
    }
}