Question

我正在尝试制作一个摇滚纸剪刀 - 蜥蜴游戏。我一直在学习if / else语句。我试图这样做，以便如果player1输入一个无效的命令，那么它将打印出“抱歉，这不是一个有效的命令”，就像使用else语句一样。如果两个玩家输入一个命令而一个是错误的，那么它是有效的，但如果只是玩家1的话。你能帮我搞清楚我应该做些什么吗？这是我的代码：

    package csc212hw03;
    import java.util.Scanner;

    public class Main {

public static void main(String[] args) {
    String player1;
    String player2;
    String player1Choice;
    String player2Choice;
    String line;

           // “1” for Paper
    //“2” for Rock
    //“3” for Spock
    //“4” for Lizard
    //“5”for Scissors
   Scanner kb = new Scanner(System.in);
   System.out.println("Player 1, please enter your name:");
   player1 = kb.nextLine();

   System.out.println("Player 2, please enter your name:");
   player2 = kb.nextLine();

   System.out.println(player1 + ", please enter your command:");
   player1Choice = kb.nextLine();

   System.out.println(player2 + ", please enter your command:");
   player2Choice = kb.nextLine();

   if (player1Choice.equals("1") && player2Choice.equals("2")) {
       System.out.println(player1 + " wins! Paper covers Rock.");
       System.out.println("Thank you for playing.");
   } else if (player2Choice.equals("2") && player1Choice.equals("1")){
       System.out.println(player2 + " wins! Paper covers Rock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("1")&& player2Choice.equals("1")) {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("2")&& player2Choice.equals("2")) {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("1")&& player2Choice.equals("3")) {
       System.out.println(player1 + " wins! Paper disproves Spock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("3") && player2Choice.equals("1")) {
       System.out.println(player2 + " wins! Paper disproves Spock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("3")&& player2Choice.equals("3"))  {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("2") && player2Choice.equals("3")) {
       System.out.println(player2 + " wins! Spock vaporizes Rock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("3") && player2Choice.equals("2")) {
       System.out.println(player1 + " wins! Spock vaporizes Rock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("3") && player2Choice.equals("5")) {
       System.out.println(player1 + " wins! Spock smashes Scissors.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("3")) {
       System.out.println(player2 + " wins! Spock smashes Scissors.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("5")) {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("2") && player2Choice.equals("5")) {
       System.out.println(player1 + " wins! Rock crushes Scissors.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("2")) {
       System.out.println(player2 + " wins! Rock crushes Scissors.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("2") && player2Choice.equals("4")) {
       System.out.println(player1 + " wins! Rock crushes Lizard.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("4") && player2Choice.equals("2")) {
       System.out.println(player2 + " wins! Rock crushes Lizard.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("3") && player2Choice.equals("4")) {
       System.out.println(player2 + " wins! Lizard poisons Spock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("4") && player2Choice.equals("3")) {
       System.out.println(player1 + " wins! Lizard poisons Spock.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("1")) {
       System.out.println(player1 + " wins! Scissors cuts Paper.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("1") && player2Choice.equals("5")) {
       System.out.println(player2 + " wins! Scissors cuts Paper.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("4")) {
       System.out.println(player1 + " wins! Scissors decpitates Lizard.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("4") && player2Choice.equals("5")) {
       System.out.println(player2 + " wins! Scissors decapitates Lizard.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("5") && player2Choice.equals("5")) {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("4") && player2Choice.equals("4")) {
       System.out.println("Draw!");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("4") && player2Choice.equals("1")) {
       System.out.println(player1 + " wins! Lizard eats Paper.");
       System.out.println("Thank you for playing.");
   } else if (player1Choice.equals("1") && player2Choice.equals("4")) {
       System.out.println(player2 + " wins! Lizard eats Paper.");
       System.out.println("Thank you for playing.");
   } else {
       System.out.println("I'm sorry, this is not a valid command.");
       System.out.println("Thank you for playing.");

   }
      }
    }

Answer 1

不要只是要求玩家1选择一次，而是将其放入while循环中询问，直到他们输入有效的响应，如此

player1Choice = "";
boolean player1ChoiceValid = false;
while(!player1ChoiceValid){
    System.out.println(player1 + ", please enter your command:");
    player1Choice = kb.nextLine();
    if(player1Choice.equals("1")
            || player1Choice.equals("2")
            || player1Choice.equals("3")
            || player1Choice.equals("4")
            || player1Choice.equals("5")){
        player1ChoiceValid = true;
    }else{
        System.out.println("I'm sorry, this is not a valid command.");
    }
}

这将持续循环问题直到输入有效，这意味着它是1或2或3或4或5.这也应该对玩家2进行。

Answer 2

        while (true) {
            Scanner kb = new Scanner(System.in);
            System.out.println(player1 + ", please enter your command:");
            String player1Choice = kb.nextLine();

            if (!player1Choice.equals("1") || !player1Choice.equals("2") || !player1Choice.equals("3")
                    || !player1Choice.equals("4") || !player1.equals("5")) {
                System.out.println("Sorry, this is not a valid command");
            } else {
                break;
            }
        }

此外，您可以在if语句中考虑更优雅的方法。

如果第一个玩家输入了错误的命令，那么我怎么能这样做呢？

2 个答案: