不用正则版本
单词倒排
https://www.nowcoder.com/practice/81544a4989df4109b33c2d65037c5836
import java.util.Scanner; // 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 string = in.nextLine(); char[] charArray = string.toCharArray(); StringBuilder stringBuilder = new StringBuilder(); for (int i = 0; i < charArray.length; i++) { if (Character.isLetter(charArray[i])) { stringBuilder.append(charArray[i]); } else { // 非字母的全部换成空格 stringBuilder.append(" "); } } // 以空格切分 String[] split = stringBuilder.toString().split(" "); StringBuilder builder = new StringBuilder(); for (int i = split.length - 1; i >= 0; i--) { if (split[i].equals("")) { continue; } builder.append(split[i] + " "); } // 注意减去一个空格 System.out.println(builder.deleteCharAt(builder.length() - 1)); } }