修复Java剪刀石头布游戏中的循环逻辑与CPU出招错误

// ... (在do-while循环内)
method4(CPUchoice, userChoiceInt); // 调用方法判断胜负
if (CPUchoice == userChoiceInt) { // 冗余的平局判断
    gameTie = true;
}
// ...

public static boolean method4(int CPUchoice, int userChoiceInt) {
    boolean gameTie = false; // method4内部的局部变量
    if (CPUchoice == userChoiceInt) {
        System.out.println("It's a tie!");
        gameTie = true; // 仅修改method4内部的gameTie
    }
    // ... 其他胜负判断
    return gameTie; // 返回平局状态
}

// ... (在do-while循环内)
// 调用method4，并将其返回值赋给main方法中的gameTie变量
gameTie = method4(CPUchoice, userChoiceInt);
// 移除此处冗余的平局判断，因为method4已经处理并返回了结果
// if (CPUchoice == userChoiceInt) {
//     gameTie = true;
// }
// ...

public static int method1() {
    Random rand = new Random();
    int CPUchoice = rand.nextInt(2); // 问题所在：只生成0或1
    return CPUchoice;
}

public static int method1() {
    Random rand = new Random();
    int CPUchoice = rand.nextInt(3); // 修正：生成0, 1, 2
    return CPUchoice;
}

import java.util.Random;
import java.util.Scanner;

public class Lab9_2 {
    public static void main(String[] args) {
        System.out.println("This program plays Rock-Paper-Scissors against the computer.\n"
                         + "When there is a tie, the game will restart until a winner is chosen.");

        boolean gameTie; // 不再初始化为false，因为它会在循环内被method4赋值
        do {
            int CPUchoice = method1(); // 生成CPU的出招 (0=rock, 1=paper, 2=scissors)
            int userChoiceInt = method2(); // 获取用户的出招 (0=rock, 1=paper, 2=scissors)

            method3(CPUchoice); // 输出CPU的出招

            // 关键修正：接收method4的返回值来更新main方法中的gameTie
            gameTie = method4(CPUchoice, userChoiceInt); 

        } while(gameTie); // 循环条件简化为 gameTie

        System.out.println("\nGame over!"); // 游戏结束后打印结束语
    }

    public static int method1() {
        // 生成随机数 0-2，代表CPU的出招
        // 0=rock, 1=paper, 2=scissors
        Random rand = new Random();
        int CPUchoice = rand.nextInt(3); // 修正：生成0, 1, 2
        return CPUchoice;
    }

    public static int method2() {
        // 获取用户的出招，包含输入校验
        Scanner kb = new Scanner(System.in);
        boolean uInput; // 安全输入标记
        char userInputChar; // 用户输入的字符
        int userChoiceInt = 0; // 用户的出招，整数表示

        do { // 循环直到用户输入有效
            System.out.println("\n\nPlease input your choice (R for Rock, P for Paper, S for Scissors):");
            userInputChar = Character.toLowerCase(kb.next().charAt(0)); // 获取并转换为小写

            if(userInputChar == 'r') { 
                userChoiceInt = 0; // rock
                uInput = true;
            } else if(userInputChar == 'p') { 
                userChoiceInt = 1; // paper
                uInput = true;
            } else if(userInputChar == 's') { 
                userChoiceInt = 2; // scissors
                uInput = true;
            } else {
                System.out.println("Sorry, that's not a valid play. Please try again.");
                uInput = false;
            }
        } while (!uInput); // 当输入不安全时继续循环

        // kb.close(); // 通常不在这里关闭Scanner，因为它可能在main方法中被重用
        return userChoiceInt; 
    }

    public static void method3(int CPUchoice) {
        // 输出CPU的出招
        String CPUchoiceStr = "";
        if (CPUchoice == 0) {
            CPUchoiceStr = "rock.";
        } else if (CPUchoice == 1) {
            CPUchoiceStr = "paper.";
        } else if (CPUchoice == 2) {
            CPUchoiceStr = "scissors.";
        }
        System.out.println("The CPU played " + CPUchoiceStr);
    }

    public static boolean method4(int CPUchoice, int userChoiceInt) {
        // 比较CPU和用户的出招，计算并输出胜负，返回是否平局
        boolean gameTie = false; // method4内部的局部变量

        if (CPUchoice == userChoiceInt) {
            // 平局
            System.out.println("It's a tie!");
            gameTie = true;
        } else if ((CPUchoice == 0) && (userChoiceInt == 1)) { // CPU=rock, User=paper
            System.out.println("Paper covers rock. You win!");
        } else if ((CPUchoice == 0) && (userChoiceInt == 2)) { // CPU=rock, User=scissors
            System.out.println("Rock breaks scissors. You lose.");
        } else if ((CPUchoice == 1) && (userChoiceInt == 0)) { // CPU=paper, User=rock
            System.out.println("Paper covers rock. You lose.");
        } else if ((CPUchoice == 1) && (userChoiceInt == 2)) { // CPU=paper, User=scissors
            System.out.println("Scissors cuts paper. You win!");
        } else if ((CPUchoice == 2) && (userChoiceInt == 0)) { // CPU=scissors, User=rock
            System.out.println("Rock breaks scissors. You win!");
        } else if ((CPUchoice == 2) && (userChoiceInt == 1)) { // CPU=scissors, User=paper
            System.out.println("Scissors cuts paper. You lose.");
        }
        // 对于非平局情况，gameTie保持为false，这是正确的
        return gameTie;
    }
}