如何在Java猜数字游戏中实现‘end game’终止功能并避免输入崩溃

阿华AIGC实验室

2026-4-29

解决猜数字游戏中输入"end game"崩溃的问题

嘿，我完全懂你遇到的头疼问题——用nextInt()读取输入时，只要用户敲入"end game"这类字符串，程序直接就因类型不匹配崩了。这是因为nextInt()只认整数，碰到非数字输入就会触发异常，咱们一步步来搞定它：

问题根源

Scanner.nextInt()会强制把输入内容解析成整数，如果输入的是像"end game"这样的字符串，它就会抛出InputMismatchException，而且错误的输入还会留在Scanner的缓冲区里，后续读取操作也会跟着出问题。

解决方案思路

我们需要先捕获用户的全部输入内容，再判断是数字还是结束指令：

用Scanner.nextLine()代替nextInt()，这样不管用户输入数字还是字符串都能完整获取。
尝试把读取到的字符串转换成整数：
- 转换成功：就用这个数字作为猜测值继续游戏。
- 转换失败：检查是不是"end game"，是的话跳回主菜单；不是的话提示用户输入有效内容。
处理输入缓冲区的换行残留：比如用next()之后，缓冲区会留下换行符，得用nextLine()消耗掉，避免后续读取空内容。

修改后的完整代码（重点优化`number`方法）

import java.util.Scanner;

public class TwoGames {
    public static void main(String[] args) {
        // 主菜单
        Scanner scan = new Scanner(System.in);
        System.out.println("Choose the game\nType 'letter' or 'number' to choose the game");
        String userAnswer = scan.next();
        scan.nextLine(); // 消耗next()后的换行符，避免影响后续nextLine()
        if (userAnswer.equalsIgnoreCase("number")) {
            number(args);
        } else if(userAnswer.equalsIgnoreCase("letter")){
            letter(args);
        }
        scan.close();
    }

    public static void letter (String[] args) {
        Scanner scan = new Scanner(System.in);
        String playAgain = "";
        String returnToMenu = "";
        int numberOfTries = 0;
        do {
            System.out.println("Guess the Letter");
            char randomLetter = (char) (Math.random() * 26 + 65);
            char enteredLetter = 0;
            while(true){
                String input = scan.nextLine().trim();
                if(input.isEmpty()){
                    System.out.println("Please enter a valid letter!");
                    continue;
                }
                enteredLetter = Character.toUpperCase(input.charAt(0));
                numberOfTries++;
                if(enteredLetter == randomLetter) {
                    System.out.println("Correct Guess");
                    System.out.println("The letter is:" + randomLetter);
                    System.out.println("It only took you " + numberOfTries + " tries! Good work!");
                    break;
                } else if(enteredLetter > randomLetter) {
                    System.out.println("Incorrect Guess");
                    System.out.println("The letter entered is too high");
                } else if(enteredLetter < randomLetter) {
                    System.out.println("Incorrect Guess");
                    System.out.println("The letter entered is too low");
                }
            }
            System.out.println("Would you like to play again (y/n)?");
            playAgain = scan.next();
            scan.nextLine(); // 消耗换行符
        } while (playAgain.equalsIgnoreCase("y"));
        System.out.println("Thank you for playing! Goodbye!\nType 'return' to return to main menu");
        returnToMenu = scan.next();
        if (returnToMenu.equalsIgnoreCase("return")) main(args);
        scan.close();
    }

    public static void number(String[] args) {
        Scanner scan = new Scanner(System.in);
        String playAgain = "";
        String returnToMenu = "";
        do {
            int theNumber = (int)(Math.random() * 100 + 1);
            int numberOfTries = 0;
            boolean isGameRunning = true;
            while (isGameRunning) {
                System.out.println("Guess a number between 1 and 100 (or type 'end game' to quit to main menu):");
                String input = scan.nextLine().trim();

                // 检查是否是结束游戏指令
                if(input.equalsIgnoreCase("end game")){
                    isGameRunning = false;
                    main(args); // 跳回主菜单
                    continue;
                }

                // 尝试转换输入为整数
                Integer guess = null;
                try{
                    guess = Integer.parseInt(input);
                } catch(NumberFormatException e){
                    System.out.println("Invalid input! Please enter a number or 'end game' to quit.");
                    continue;
                }

                // 验证数字范围
                if(guess < 1 || guess > 100){
                    System.out.println("Please enter a number between 1 and 100!");
                    continue;
                }

                numberOfTries++;
                if (guess < theNumber) {
                    System.out.println(guess + " is too low. Try again.");
                } else if (guess > theNumber) {
                    System.out.println(guess + " is too high. Try again.");
                } else {
                    System.out.println(guess + " is correct. You win!");
                    System.out.println("It only took you " + numberOfTries + " tries! Good work!");
                    isGameRunning = false; // 猜对后结束当前游戏轮次
                }
            }

            System.out.println("Would you like to play again (y/n)?");
            playAgain = scan.next();
            scan.nextLine(); // 消耗换行符
        } while (playAgain.equalsIgnoreCase("y"));

        System.out.println("Thank you for playing! Goodbye!\nType 'return' to return to main menu");
        returnToMenu = scan.next();
        if (returnToMenu.equalsIgnoreCase("return")) main(args);
        scan.close();
    }
}