CS初学者尝试用java制作一个绞刑者游戏

import java.util.Scanner;

public class HangmanGame {
    private static final String[] WORDS = {"apple", "banana", "orange", "watermelon"};  // 隐藏单词列表
    private String word;  // 当前隐藏单词
    private StringBuilder guessedLetters;  // 玩家已猜测的字母
    private int attemptsLeft;  // 剩余尝试次数
    private boolean gameWon;  // 游戏是否胜利

    public HangmanGame() {
        word = WORDS[(int) (Math.random() * WORDS.length)];
        guessedLetters = new StringBuilder();
        attemptsLeft = 6;
        gameWon = false;
    }

    public void play() {
        Scanner scanner = new Scanner(System.in);

        while (attemptsLeft > 0 && !gameWon) {
            System.out.println("Current word: " + getMaskedWord());
            System.out.println("Attempts left: " + attemptsLeft);

            System.out.print("Guess a letter: ");
            String guess = scanner.nextLine().toLowerCase();

            if (guess.length() != 1 || !Character.isLetter(guess.charAt(0))) {
                System.out.println("Invalid input! Please enter a single letter.");
                continue;
            }

            char letter = guess.charAt(0);
            if (guessedLetters.toString().contains(guess)) {
                System.out.println("You've already guessed this letter.");
                continue;
            }

            guessedLetters.append(letter);

            if (word.contains(guess)) {
                System.out.println("Correct guess!");
                if (getMaskedWord().equals(word)) {
                    gameWon = true;
                }
            } else {
                System.out.println("Wrong guess!");
                attemptsLeft--;
            }
            System.out.println();
        }

        if (gameWon) {
            System.out.println("Congratulations! You won!");
        } else {
            System.out.println("Game over! The word was: " + word);
        }

        scanner.close();
    }

    private String getMaskedWord() {
        StringBuilder maskedWord = new StringBuilder();
        for (int i = 0; i < word.length(); i++) {
            char letter = word.charAt(i);
            if (guessedLetters.toString().contains(Character.toString(letter))) {
                maskedWord.append(letter);
            } else {
                maskedWord.append("_");
            }
            maskedWord.append(" ");
        }
        return maskedWord.toString();
    }

    public static void main(String[] args) {
        HangmanGame game = new HangmanGame();
        game.play();
    }
}