Question

所以我正在制作每个人都很有趣的游戏“Rock，Paper，Scissors”我让一切正常，除了让while循环在停止之前重复3次。那么它会重复3次并停止，但第2次和第3次重复变量不会改变。看看代码并告诉我我做错了什么。 **更新：现在我已经完成了所有工作，如何获得这个“Q”字符串来终止循环？

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

public class RockPaperScissors
{

    /**
     * (Insert a brief description that describes the purpose of this method)
     * 
     * @param args
     */
    public static void main(String[] args)
    {
        int compint;
        String usermove = "";
        String compmove = "";
        String winner = "";
        int count = 0;


        Scanner in = new Scanner(System.in);
        Random gen = new Random();

        System.out.println("Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: ");
        int input = in.nextInt();       

        while (count < 3)
        {
            compint = gen.nextInt(3) + 1;

            if (input == 1)
            {
                usermove = "Rock";
            }
            else if (input == 2)
            {
                usermove = "Paper";
            }
            else if (input == 3)
            {
                usermove = "Scissors";
            }

            if (compint == 1)
            {
                compmove = "Rock";
            }
            else if (compint == 2)
            {
                compmove = "Paper";
            }
            else if (compint == 3)
            {
                compmove = "Scissors";
            }

            if (compint == input)
            {
                winner = "TIE";
            }
            else if (compint == 1 && input == 3)
            {
                winner = "COMPUTER";
            }
            else if (compint == 2 && input == 1)
            {
                winner = "COMPUTER";
            }
            else if (compint == 3 && input == 2)
            {
                winner = "COMPUTER";
            }
            else
            {
                winner = "USER";
            }

            System.out.print("Computer: " + compmove + " | ");
            System.out.print("You: " + usermove + " | ");
            System.out.println("Winner: " + winner);
            System.out.println();
            System.out.println("Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: ");
            input = in.nextInt();
            count++;

        }
    }
}

输出：

Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: 
1
Computer: Scissors | You: Rock | Winner: USER

Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: 
2
Computer: Rock | You: Paper | Winner: USER

Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: 
Q
Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at RockPaperScissors.main(RockPaperScissors.java:102)

Answer 1

实际使用输入任何内容的逻辑 - 所有那些if语句 - 都在循环之外。通过每次迭代看，没有任何逻辑实际上没有被执行。一切都只是先发生。试试这个：

for (int count=0; count < 3; count++)
{
    int input = in.nextInt();
    int compint = gen.nextInt(3) + 1;

    // all the if statements and printing here
}

**更新：既然我已经完成了所有工作，我如何获得这个“Q”字符串来终止循环？

您在输入Q时收到InputMismatchException，但代码会调用Scanner#nextInt()。文档很清楚问题是什么：

由Scanner抛出，表示检索到的令牌与预期类型的模式不匹配，或者令牌超出预期类型的范围。

这基本上是Scanner告诉你的方式“你要求int，但下一个标记不是一个。”您可以在nextInt()调用之前使用Scanner#hasNextInt()添加其他检查，以验证实际的下一个标记是否为int。如果它不是int，那么你可以计划将其解析为字符串。

所以不要这样：

input = in.nextInt();

做这样的事情：

if (in.hasNextInt())
{
    input = in.nextInt();
} else if (in.hasNext("Q")) {
    // quit
}

Answer 2

好像你想用do - while loop 它会工作：

do{
       compint = gen.nextInt(3) + 1;

        System.out.println("Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: ");
        int input = in.nextInt();

        if (input == 1)
        {
            usermove = "Rock";
        }
        else if (input == 2)
        {
            usermove = "Paper";
        }
        else if (input == 3)
        {
            usermove = "Scissors";
        }

        if (compint == 1)
        {
            compmove = "Rock";
        }
        else if (compint == 2)
        {
            compmove = "Paper";
        }
        else if (compint == 3)
        {
            compmove = "Scissors";
        }

        if (compint == input)
        {
            winner = "TIE";
        }
        else if (compint == 1 && input == 3)
        {
            winner = "COMPUTER";
        }
        else if (compint == 2 && input == 1)
        {
            winner = "COMPUTER";
        }
        else if (compint == 3 && input == 2)
        {
            winner = "COMPUTER";
        }
        else
        {
            winner = "USER";
        }

            System.out.print("Computer: " + compmove + " | ");
            System.out.print("You: " + usermove + " | ");
            System.out.println("Winner: " + winner);
            System.out.println("Enter Rock(1), Paper(2), Scissors(3) {Q to quit]: ");
            input = in.nextInt();
            count++;

        }while (count < 3);

Answer 3

特别是，你的“while”循环除了打印之外不对胜利者做任何事情，因此无论输入如何，赢家对于整个游戏都保持不变。这可能是开始“调试”的好地方。

如何创建String int终止符？

3 个答案: