如何使这个Java程序循环？

我是一个编程新手，我需要添加一个JOptionPane，上面写着：“再玩一次？”。选择“是”和“否”

如果“是”，游戏将重新开始。如果“否”，游戏将终止

任何帮助都将不胜感激。提前谢谢

import javax.swing.JOptionPane;
import java.util.Random;

public class JackAndPoy {


    public static void main(String[] args)
    {
        String computerSide,
               userSide;

         JOptionPane.showMessageDialog(null, " Play the Game \"Rock, Paper,  Scissors?\"");

         computerSide = ComputerChoice();
         userSide = UserChoice();


        if (userSide != null)
        {
            JOptionPane.showMessageDialog(null, "The computer's choice is " + computerSide + ".");

            Winner(computerSide, userSide);
        }

         else {
            JOptionPane.showMessageDialog(null, "Error: Improper UserEntry. Please enter either" + 
                                        " 'rock', 'paper', or'scissors'.");
        }
    }

     public static String ComputerChoice()
     {
         byte computerChoice;

         String computerChoiceString = "";

         Random choiceGenerator = new Random();

         computerChoice = (byte)(choiceGenerator.nextInt(3) + 1);

         switch (computerChoice)
         {


             case 1:
             { 
                 computerChoiceString = "rock";
                 break;
             }


             case 2:
             {
                computerChoiceString = "paper";
                break;
             }

             case 3:
             {
                computerChoiceString = "scissors";
                break;
             }

         }

         return computerChoiceString;
    }

    public static String UserChoice()
    {
        String userChoice,
               userChoiceLowerCase;

        userChoice =
                JOptionPane.showInputDialog("Choice: [rock][paper][scissors]");

        if (userChoice.equalsIgnoreCase("rock") || userChoice.equalsIgnoreCase("paper")
                || userChoice.equalsIgnoreCase("scissors"))
        {
            userChoiceLowerCase = userChoice.toLowerCase();
        }

        else {
            userChoiceLowerCase = null;
        }

        return userChoiceLowerCase;
    }

 public static void Winner(String computerSide, String userSide)
  {

        if (computerSide.equals(userSide)) {
            JOptionPane.showMessageDialog(null, "The game has to be played again, because we have a tie.");
        }

            else if (computerSide.equalsIgnoreCase("rock") && userSide.equalsIgnoreCase("paper")) {
            JOptionPane.showMessageDialog(null, "You win. Paper covers rock.");
        }


        else if (computerSide.equalsIgnoreCase("rock") && userSide.equalsIgnoreCase("scissors")) {
            JOptionPane.showMessageDialog(null, "You lose. Rock crushes scissors.");
        }


        else if (computerSide.equalsIgnoreCase("paper") && userSide.equalsIgnoreCase("rock")) {
            JOptionPane.showMessageDialog(null, "You lose. Paper covers rock.");
        }


        else if (computerSide.equalsIgnoreCase("paper") && userSide.equalsIgnoreCase("scissors")) {
            JOptionPane.showMessageDialog(null, "You win. Scissors cuts paper.");
        }


        else if (computerSide.equalsIgnoreCase("scissors") && userSide.equalsIgnoreCase("rock")) {
            JOptionPane.showMessageDialog(null, "You win. Rock crushes scissors.");
        }


        else {
            JOptionPane.showMessageDialog(null, "You lose. Scissors cuts paper.");
        }
    }
}

---

您需要一个do-while循环，该循环执行一个操作，然后检查再次执行该操作的条件。这与常规while循环不同。do while循环必须至少执行一次该代码块。因此，改变你的主要方法如下：

public static void main(String[] args)
    {
    JOptionPane.showMessageDialog(null,
            " Play the Game \"Rock, Paper,  Scissors?\"");

    String computerSide, userSide;

    do
        {
        computerSide = ComputerChoice();
        userSide = UserChoice();
        if(userSide != null)
            {
            JOptionPane.showMessageDialog(null, "The computer's choice is "
                    + computerSide + ".");
            Winner(computerSide, userSide);
            }
        else
            {
            JOptionPane.showMessageDialog(null,
                    "Error: Improper UserEntry. Please enter either"
                            + " 'rock', 'paper', or'scissors'.");
            }
        }
    while(JOptionPane.showConfirmDialog(null, "Play Again?", "Rock-Paper-Scissors", JOptionPane.YES_NO_OPTION) == 0);
    }

查看do-while循环。您还可以将while循环与布尔值一起使用，如果玩家说“否”，则布尔值为false，否则为true。