题解 | #图片整理#

import java.util.Collections;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.stream.Collectors;

// 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);
        String str = in.nextLine();
        System.out.println(make(str));
    }

    private static String make(String str) {
        int len = str.length();
        LinkedList<Integer> list = new LinkedList<>();
        for (int i = 0; i < len; i++) {
            list.add((int) str.charAt(i));
        }
        Collections.sort(list);
        return list.stream().map(t->String.valueOf((char)t.intValue())).collect(Collectors.joining());
    }
}