Java do-while循环异常：输入'n'偶不终止、积分耗尽未停止

核心错误分析 #

1. 循环终止逻辑完全写反：外层do-while的条件repeat.equals("n") || points != 0逻辑完全颠倒——它表示「用户输入'n' 或者 积分不等于0时继续循环」，和你期望的「输入'n'终止、积分<=0终止」完全相反。
2. 积分耗尽无法终止：原条件里points !=0会导致积分变成负数时，循环依然满足条件继续执行，因为负数不等于0。

额外优化点 #

• 内层赌金额度校验只判断了gambleAmount > points，没处理用户输入负数的情况
• 规则说明里的Numbers 8-13未标注是high，逻辑不完整
• 随机数为7时，用户猜0或1都会输，但没有明确提示原因

修复后的完整代码 #

package highlow;

import java.util.Scanner;

public class Highlow {

    public static void Rules() {
        System.out.println("RULES:");
        System.out.println("Numbers 1-6 are low ");
        System.out.println("Numbers 8-13 are high"); // 补全规则说明
        System.out.println("Number 7 is neither high or low\n");
    }

    public static void main(String[] args) {
        int number;
        int gambleAmount;
        int prediction;
        int correctRange;
        int winnings;
        int points;
        int numberOfGuesses = 0;
        String repeat;
        Scanner input = new Scanner(System.in);
        points = 1000;
        System.out.print("High Low Game\n\n");
        Rules();
        do {
            number = (int) (13 * Math.random() + 1);
            if (number > 7) {
                correctRange = 1;
            } else if (number < 7) {
                correctRange = 0;
            } else {
                correctRange = -1;
            }
            numberOfGuesses += 1;
            System.out.println("You have " + points + " points");
            
            // 修复赌金额度校验：增加负数/0判断
            do {
                System.out.println("Please insert a valid number of points");
                System.out.print("How many points would you like to gamble: ");
                gambleAmount = input.nextInt();
            } while (gambleAmount > points || gambleAmount <= 0);
            
            System.out.print("Predict [1=high, 0=low]: ");
            prediction = input.nextInt();
            
            if (prediction == correctRange) {
                winnings = gambleAmount * 2;
                points = points + winnings;
                System.out.println("The number was " + number);
                System.out.print("You win!\n\n");
            } else {
                points = points - gambleAmount;
                System.out.println("The number was " + number);
                // 增加7的输局提示
                if (correctRange == -1) {
                    System.out.println("Result is neutral (7), so you lose!\n");
                } else {
                    System.out.print("You lose\n\n");
                }
            }
            
            // 积分耗尽直接结束，无需询问
            if (points <= 0) {
                System.out.println("You have no points left, game over!");
                break;
            }
            
            System.out.print("Would you like to play again ('n' for no and 'y' for yes): ");
            repeat = input.next();
        // 修复循环条件：仅当用户输入'y'（不区分大小写）且积分>0时继续
        } while (repeat.equalsIgnoreCase("y") && points > 0);
        
        System.out.print("You had " + numberOfGuesses + " guesses");
        input.close(); // 关闭Scanner避免资源泄漏
    }
}

关键修复说明 #

• 外层循环条件改为repeat.equalsIgnoreCase("y") && points > 0：严格控制只有用户想继续且还有积分时，才执行下一轮游戏
• 内层赌金额度校验增加gambleAmount <=0判断：防止用户输入无效的负数或0
• 增加积分<=0时的主动跳出逻辑：用户没钱后直接结束游戏，无需多余询问
• 补全规则说明和7的输局提示：提升游戏体验
• 关闭Scanner：避免资源泄漏

内容的提问来源于stack exchange，提问作者Tristan Day