注释详解 | #字符串合并处理#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            String str = in.nextLine();
            str = str.replace(" ", "");
            char[] chars = str.toCharArray();
            int count = chars.length / 2;
            // 考虑总数量不是偶数的情况
            int count2 = chars.length % 2;
            String[] string1 = new String[count + count2];
            String[] string2 = new String[count];
//            TreeSet<String> string1 = new TreeSet<>();
//            TreeSet<String> string2 = new TreeSet<>();
            // 分类排序
            for (int i1 = 0, i2 = 0, i = 0; i < chars.length; i++) {
                String s = String.valueOf(chars[i]);
                if (i % 2 == 0) {
                    // 奇数位
                    string1[i1] = s;
                    i1++;
                } else {
                    // 偶数位
                    string2[i2] = s;
                    i2++;
                }
            }

            Arrays.sort(string1);
            Arrays.sort(string2);
            // 重组
            for (int i1 = 0, i2 = 0, i = 0; i < chars.length; i++) {
                String s = "";
                if (i % 2 == 0) {
                    // 奇数位
                    s = string1[i1];
                    i1++;
                } else {
                    s = string2[i2];
                    i2++;
                }

                // 不在需要操作的范围
                if(s.replaceAll("[0-9]","").replaceAll("[a-f]","").replaceAll("[A-F]","").equals(s)){
                    System.out.print(s);
                    continue;
                }
                // 不属于0-9
                if (s.replaceAll("[0-9]", "").equals(s)) {
                    // 将16进制转为10进制
                    s = String.valueOf(Integer.parseInt(s, 16));
                }
                // 10进制转为2进制
                String to2 = Integer.toBinaryString(Integer.parseInt(s));
                // 补0
                if (to2.length() < 4) {
                    StringBuilder stringBuilder = new StringBuilder(to2);
                    for (int j = to2.length(); j < 4; j++) {
                        stringBuilder.insert(0, 0);
                    }
                    to2 = stringBuilder.toString();
                }

                // 反转
                StringBuilder reverse = new StringBuilder(to2).reverse();

                // 2进制转为10进制
                int to10 = Integer.parseInt(reverse.toString(), 2);
                // 不属于0-9
                if (!(to10 >= 0 && to10 <= 9)) {
                    // 转为16进制
                    String result = Integer.toHexString(to10);
                    System.out.print(result.toUpperCase());
                } else {
                    System.out.print(to10);
                }
            }
        }
    }
}