题解 | #字符串排序#

import java.util.Scanner;

import java.util.List;
import java.util.ArrayList;

// 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);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String line = in.nextLine();
            char[] lineArray = line.toCharArray();
            List<Integer> index = new ArrayList<Integer>();
            for (int i = 0; i < lineArray.length; i++) {
                if (!Character.isLetter(lineArray[i])) {
                    index.add(i);
                }
            }

            String newLine = line.replaceAll("[^a-z^A-Z]+", "");
            char[] chars = newLine.toCharArray();

            // 字符串排序
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < 26; i++) {
                for (int j = 0; j < chars.length; j++) {
                    if ((char)((int)('a') + i) == chars[j]) {
                        sb.append(chars[j]);
                    }
                    if ((char)((int)('A') + i) == chars[j]) {
                        sb.append(chars[j]);
                    }
                }
            }

            char[] result = new char[line.length()];
            int k = 0;
            for (int i = 0; i < line.length(); i++) {
                if (!Character.isLetter(line.charAt(i))) {
                    result[i] = line.charAt(i);
                } else {
                    result[i] = sb.toString().charAt(k);
                    k++;
                }
            }
            for (int i = 0; i < result.length; i++)
                System.out.print(result[i]);
        }
    }
}