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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        String aa= in.nextLine();
        //找出字母的list
        List<Character> list =new ArrayList<>();
	 //找出不是字母的下标
        List<Integer> notletter =new ArrayList<>();
        for(int i=0;i<aa.length();i++){
            if(Character.isLetter(aa.charAt(i))){
                list.add(aa.charAt(i));
            }else {
                notletter.add(i);
            }

        }
	 //不区分大小写排序
        list.sort(new Comparator<Character>(){
            @Override
            public int compare(Character o1,Character o2){
                return Character.toLowerCase(o1)-Character.toLowerCase(o2);
            }
        });
	 //排好序的进行添加
        StringBuilder stringBuilder =new StringBuilder();
        for (Character character : list) {
            stringBuilder.append(character);
        }
	 //插入不是字母的字符
        for (Integer integer : notletter) {
            stringBuilder.insert(integer,String.valueOf(aa.charAt(integer)));
        }
        System.out.println(stringBuilder.toString());
    }
}