题解 | #字符串排序#

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String str = sc.nextLine();
            System.out.println(sort(str));
        }
        
    }
    
    public static String sort(String str){
        //将字符串转为字符数组
        char[] arr = str.toCharArray();
        //取出字符数组中是字母的集合
        ArrayList<Character> list = new ArrayList<Character>();
        for(char c : arr){
            if(Character.isLetter(c)){
                list.add(c);
                
            }
        }
        //按照小写字母排序
        list.sort((a,b) -> {return Character.toLowerCase(a) - Character.toLowerCase(b);});
        
        StringBuilder sb = new StringBuilder();
        int i = 0;
        for(char c :arr){
            if(Character.isLetter(c)){
                sb.append(list.get(i));
                i++;
            }else{
                sb.append(c);
            }
        }
        
        return sb.toString();
    }
}