题解 | #字符串排序#

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 sc=new Scanner(System.in);
        String str=sc.nextLine();
        sort(str);
    }
    public static void sort(String str){
        ArrayList<String> list=new ArrayList<>();
        for (String s : str.split("")) {
            if(s.matches("[a-z]||[A-Z]")){
                list.add(s);
            }
        }
        Collections.sort(list,String::compareToIgnoreCase);

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