题解 | #字符串排序#

先存入list排序，用另一个list记录非字母下表，然后再插入

public class Main{
 public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String str = sc.nextLine();
            char[] chars = str.toCharArray();
           
            System.out.println(sort(chars));
        }
      
    }

    
    public static StringBuilder sort(char[] chars){
        // 用于记录非字母下标
        List<Integer> indexList = new ArrayList<>();
        List<Character> listChars= new ArrayList<>();
        for(int i=0;i<chars.length;i++){
            if(Character.isLetter(chars[i])){
                listChars.add(chars[i]);
            }else{
                indexList.add(i);
            }
        }
        // 字母排序
        Collections.sort(listChars, new Comparator<Character>() {
            @Override
            public int compare(Character o1, Character o2) {
                return Character.toLowerCase(o1)-Character.toLowerCase(o2);
            }
        });
        
        StringBuilder builder = new StringBuilder();
        for (Character listChar : listChars) {
            builder.append(listChar);
        }
        for (Integer integer : indexList) {
           // 插入非字母
            builder.insert(integer,String.valueOf(chars[integer]));
        }
       return builder;
    }
}