题解 | #字符串排序#,看了大佬写的秒懂

import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (sc.hasNextLine()){
            ArrayList<Character> list = new ArrayList<>();
            String line = sc.nextLine();
            for (char c : line.toCharArray()) {
                if(Character.isLetter(c)){
                    list.add(c);
                }
            }
            list.sort(new Comparator<Character>() {
                @Override
                public int compare(Character o1, Character o2) {
                    // 全部转为小写比较，如果相同，位置不变
                    return Character.toLowerCase(o1) - Character.toLowerCase(o2);
                }
            });

            StringBuffer buffer = new StringBuffer();
            int i = 0;
            for (char c : line.toCharArray()) {
                if(Character.isLetter(c)){
                    buffer.append(list.get(i));
                    i++;
                }else {
                    buffer.append(c);
                }
            }
            System.out.println(buffer);
        }

    }
}