字符串排序（）

import java.util.Scanner;


public class Main{
    
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String str = sc.nextLine();
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < str.length(); i++){
                char c = str.charAt(i);
                if(Character.isLetter(c)){
                    sb.append(c);
                }
            }
            //冒泡排序
            char[] cs = sb.toString().toCharArray();
            for(int i = 0; i < cs.length; i++){
                for(int j = 0; j < cs.length - i - 1; j++){
                        if(Character.toLowerCase(cs[j]) - Character.toLowerCase(cs[j + 1]) > 0){
                            char temp = cs[j];
                            cs[j] = cs[j + 1];
                            cs[j + 1] = temp;
                     }
                }
            }
            StringBuilder result = new StringBuilder();
            int index = 0;
            for(int i = 0; i < str.length(); i++){
                char c = str.charAt(i);
                if(Character.isLetter(c)){
                    result.append(cs[index]);
                    index++;
                }else{
                    result.append(c);
                }
            }
            
            System.out.println(result.toString());
        }
        
        sc.close();
    }
}