题解 | #字符串排序#

自定义排序

思路见代码注释

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);

        char[] arr = br.readLine().toCharArray();

        // 收集字符串中的字母
        List<Character> list = new ArrayList<>(arr.length);
        for (char c : arr) {
            if (Character.isLetter(c)) {
                list.add(c);
            }
        }
        // 将字母按要求排序
        list.sort((a, b) -> Character.toLowerCase(a) - Character.toLowerCase(b));

        StringBuilder builder = new StringBuilder();
        for (int i = 0, j = 0; i < arr.length; i++) {
            if (Character.isLetter(arr[i])) {
                // 字母按排好序的拼接
                builder.append(list.get(j));
                j++;
            } else {
                // 非字母直接拼接
                builder.append(arr[i]);
            }
        }
        pw.println(builder.toString());

        pw.flush();
        pw.close();
        br.close();
    }
}