题解 | 字符串排序

import java.lang.Character;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

// 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 in = new Scanner(System.in);
        char[] charArr = in.nextLine().toCharArray();
        List<Character> list = new ArrayList<>();
        for (char c : charArr) {
            if (Character.isLetter(c)) {
                list.add(c);
            }
        }
        list.sort(Comparator.comparingInt(Character::toLowerCase));
        int listIndex=0;
        for (int i=0;i<charArr.length;i++) {
            if(Character.isLetter(charArr[i])){
                charArr[i]=list.get(listIndex++);
            }
            System.out.print(charArr[i]);
        }
    }
}