Question

我是非常擅长编码，并试图根据我在这里看到的那个制作一个石头剪刀代码。但是，当系统在打印出计算机播放的内容后输出游戏结果时，它就不会打印出来。有任何想法吗？谢谢！

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

public class Rock {

    public static void main(String[] args) {  

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

        System.out.println("Hey, let's play Rock, Paper, Scissors!\n" + 
                   "Please enter a move.\n" + "Rock = R, Paper" + 
                   "= P, and Scissors = S.");

        int computerInt = gen.nextInt(3)+1;

        String computerPlay = "";
        if (computerInt == 1)
            computerPlay = "R";
        else if (computerInt == 2)
            computerPlay = "P";
        else if (computerInt == 3)
            computerPlay = "P";

        System.out.print("Please enter your play: ");

        String personPlay = scan.next();
        personPlay = personPlay.toUpperCase();
        System.out.println("Computer play is: " + computerPlay);

        if (personPlay.equals(computerPlay)) 
           System.out.println("It's a tie!"); 
        else if (personPlay.equals("R")) 
             if (computerPlay.equals("S")) 
              System.out.println("Rock crushes scissors. You win!!");
        else if (computerPlay.equals("P")) 
                System.out.println("Paper eats rock. You lose!!"); 
        else if (personPlay.equals("P")) 
           if (computerPlay.equals("S")) 
           System.out.println("Scissor cuts paper. You lose!!"); 
        else if (computerPlay.equals("R")) 
                System.out.println("Paper eats rock. You win!!"); 
        else if (personPlay.equals("S")) 
             if (computerPlay.equals("P")) 
             System.out.println("Scissor cuts paper. You win!!"); 
        else if (computerPlay.equals("R")) 
                System.out.println("Rock breaks scissors. You lose!!"); 
        else 
             System.out.println("Invalid user input.");
     }
}

Answer 1

if语句的嵌套是完全错误的。您的缩进（几乎有点）暗示您希望如何执行代码，但编译器根本不关心您的缩进，它只遵循java语言的规则。

多个嵌套的条件语句，如if() else if() if()，很难确定（由人类）如何执行它们。

所以：从不使用多个没有花括号的语句。（有些人甚至说要总是使用花括号，即使你只有一个陈述。）

当存在最微小的歧义时（如您编写的代码中所示），请确保始终添加花括号以确保编译器按照您的意图编译代码。

然后，您的代码将（可能）起作用。

Answer 2

编码中的两件大事就是让您的代码易于阅读和实用。那些if语句不能满足这些需求。你也不要使用花括号......使用花括号{}！这是你的代码，但我把它组织得更干净一点。另外，老实说，我不确切地知道为什么它没有在您的原始代码中打印，但这不是问题。这个有效。

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

public class RockPaperScissors {
    private static Scanner scan = new Scanner(System.in);

    public static void main(String[] args) {
        String personPlay;
        String computerPlay = "";
        int computerInt;

        Random gen = new Random();

        System.out.println("Hey, let's play Rock, Paper, Scissors!\n" + "Please enter a move.\n" + "Rock = R, Paper"
                + "= P, and Scissors = S.");

        computerInt = gen.nextInt(3) + 1;

        if (computerInt == 1) {
            computerPlay = "R";
        }
        if (computerInt == 2) {
            computerPlay = "P";
        }
        if (computerInt == 3) {
            computerPlay = "P";
        }

        System.out.print("Please enter your play: ");

        personPlay = scan.next();

        personPlay = personPlay.toUpperCase();

        System.out.println("Computer play is: " + computerPlay);
        if (personPlay.equals(computerPlay)) {
            System.out.println("It's a tie!");
        }
        if (personPlay.equals("R") && computerPlay.equals("S")) {
            System.out.println("Rock crushes scissors. You win!!");
        }
        if (personPlay.equals("R") && computerPlay.equals("P")) {
            System.out.println("Paper eats rock. You lose!!");
        }
        if (personPlay.equals("P") && computerPlay.equals("R")) {
            System.out.println("Paper eats rock. You win!!");
        }
        if (personPlay.equals("P") && computerPlay.equals("S")) {
            System.out.println("Scissor cuts paper. You lose!!");
        }
        if (personPlay.equals("S") && computerPlay.equals("R")) {
            System.out.println("Rock breaks scissors. You lose!!");
        }
        if (personPlay.equals("S") && computerPlay.equals("P")) {
            System.out.println("Scissor cuts paper. You win!!");
        }
        if (!computerPlay.equals("R") && !computerPlay.equals("P") && !computerPlay.equals("S")) {
            System.out.println("Invalid user input.");
        }

    }
}

嵌套if - else语句有问题

2 个答案: