Question

我对此很新。我刚刚开始上大学的编程课程（CS 107和CS 108 intro to java）。我的作业是在计算机和用户之间创建一个Rock，Paper Scissor游戏。我收到了关于我的compPlay字符串尚未声明的java上的错误消息。由于@caps锁定，它已经得到修复。现在，在我运行程序之后它会打印指令，但是一旦我输入输入（0,1或2），它就不会告诉我它是否是平局，如果我输了或输了。谁能发现我搞砸了？谢谢！

import java.util.Scanner;

import java.util.Random;

public class Lab3 {

    public static void main(String[] args) 
{
        String userPlay; // 0=Scissor, 1=Rock, 2=Paper
        String compPlay = ""; // 0=Scissor, 1=Rock, 2=Paper
        int compInt; // Random generated number from 0-2

        Scanner scan = new Scanner(System.in);
        Random generator = new Random();
        System.out.print("Let's play Rock, Paper, Scissor! Please enter 0 for Scissor, 1 for Rock or 2 for Paper.  ");
        System.out.println();

        // Random generated number from 0-2
        compInt = (int)(Math.random())*3;


    // Translate computer random number selected into string

    if (compInt == (0))
{
    compPlay = "Scissor";
}
    else if (compInt == (1))
{
    compPlay = "Rock";
}
    else if (compInt == (2))
{
    compPlay = "Paper";
}

    // Get user input
    System.out.println("Enter your choice ");
    userPlay = scan.next();

    // Print computer random number
    System.out.println("Computer is: " + compInt);

    // Set who wins, loses or ties

    if(userPlay.equals (compInt))
{
    System.out.println("It's a tie!");
}
    else if (userPlay.equals (1))
{
    if (compPlay.equals("0"))
    System.out.println("Computer is Scissor. You are Rock. You win!");
    else if (compPlay.equals("2"))
    System.out.println("Computer is Paper. You are Rock. You lose.");
}

    else if (userPlay.equals(2))
{
    if (compPlay.equals("Scissor"))
    System.out.println("Computer is Scissor. You are Paper. You lose.");
    else if (compPlay.equals("Rock"))
    System.out.println("Computer is Rock. You are Paper. You win!");
}
    else if (userPlay.equals(0))
{
    if (compPlay.equals("Rock"))
    System.out.println("Computer is Rock. You are Scissor. You lose.");
    else if (compPlay.equals("Paper"))
    System.out.println("computer is Paper. You are Scissor. You win!");
}

}// main
}// class

Answer 1

您不能将.equals()与字符串一起使用来与int进行比较。我建议做的是将userPlay的类型更改为int并进行以下更改。主要之后的第一行：

int userPlay;

现在将userPlay = scan.next();更改为：

userPlay = scan.nextInt();

比较userPlay时，将几个if语句更改为：

if(userPlay == compInt)
if(userPlay == 0)
if(userPlay == 2)
... etc

我认为你根本不需要字符串，因为你输入的是简单的数字，而不是像剪刀这样的字。您可以将此代码转到Code Review，他们可以帮助您改进它！我建议在数据类型之间进行更多比较！希望这有帮助。

Answer 2

如果你想编译，你需要先初始化..

String compPlay = "";

Answer 3

你是一名学生，所以你可以原谅在主要方法中写一段代码，但是当你在编程教育中走得更远时，需要考虑以下事项：< / p>

Java是一种面向对象的语言。开始尝试根据封装在对象中的行为进行思考，如下所示：

选择：

package game.rps;

/**
 * Choices for rock paper scissors
 * @author Michael
 * @link  https://stackoverflow.com/questions/26310090/assistance-with-rock-paper-scissor-game
 * @since 10/10/2014 9:42 PM
 */
public enum Choice {
    ROCK, PAPER, SCISSORS
}

成果：

package game.rps;

/**
 * Outcome for rock paper scissors
 * @author Michael
 * @link https://stackoverflow.com/questions/26310090/assistance-with-rock-paper-scissor-game
 * @since 10/10/2014 9:44 PM
 */
public enum Outcome {
    LOSE, DRAW, WIN
}

播放器代表计算机：

package game.rps;

import java.util.Random;

/**
 * Player represents the computer in the game
 * @author Michael
 * @link https://stackoverflow.com/questions/26310090/assistance-with-rock-paper-scissor-game
 * @since 10/10/2014 9:54 PM
 */
public class Player {

    private Random random;

    public Player() {
        this.random = new Random();
    }

    public Player(long seed) {
        this.random = new Random(seed);
    }

    public Choice decide() {
        int index = this.random.nextInt(Choice.values().length);
        return Choice.values()[index];
    }
}

玩游戏的驱动程序：

package game.rps;

import java.util.Scanner;

/**
 * Game loop for playing rock paper scissors
 * @author Michael
 * @link https://stackoverflow.com/questions/26310090/assistance-with-rock-paper-scissor-game
 * @since 10/10/2014 9:43 PM
 */
public class Game {

    public static void main(String[] args) {
        String input;
        Scanner in = new Scanner(System.in);
        Game game = new Game();
        Player player = new Player();
        do {
            System.out.println("ROCK, PAPER, SCISSORS, or QUIT: ");
            input = in.nextLine().trim();
            Choice human = Choice.valueOf(input);
            Choice computer = player.decide();
            System.out.println(String.format("computer: %s", computer));
            System.out.println(String.format("human   : %s", human));
            System.out.println(String.format("outcome : %s", game.play(human, computer)));
        } while (!"QUIT".equalsIgnoreCase(input));
    }

    public  Outcome play(Choice player1, Choice player2) {
        if (player1 == player2) {
            return Outcome.DRAW;
        } else {
            if (player1 == Choice.ROCK) {
                return (player2 == Choice.PAPER ? Outcome.LOSE : Outcome.WIN);
            } else if (player1 == Choice.PAPER) {
                return (player2 == Choice.SCISSORS ? Outcome.LOSE : Outcome.WIN);
            } else {
                return (player2 == Choice.ROCK ? Outcome.LOSE : Outcome.WIN);
            }
        }
    }
}

协助Rock，Paper，Scissor游戏

3 个答案: