java - boolean 值不会WHILE循环java编程

Question

我遇到了一个我还没有遇到的问题。我用 Java 编写了一个猜谜游戏来猜测 1 到 1000 之间的数字。程序应该循环直到玩家决定他或她不再想玩为止。但是我无法让它循环。如果我取出程序底部的 Scanner 类，它会很好地循环，但我需要扫描器类来完成我类(class)要求的程序。如果用户在扫描器类中键入“no”，while 循环变量将设置为 false，程序将正常终止。但是如果用户选择"is"并且 while 循环变量保持为真，我就无法让它循环。输入“yes”后，程序就暂停了，什么也没有发生，程序也没有结束。任何帮助将不胜感激。

import javax.swing.*;
import java.util.*;
public class RandomGuess3
{
   public static void main(String[] args)
   {
      String userGuess;
      String playAgain;
      int guessNum;
      int randomNum = (1+(int)(Math.random()*1000));
      int guessCount = 0;
      boolean correct = false;
      boolean startGame = true;
      boolean newGame = false;

         if(launchGame() == true)
            startGame = true;
         while(startGame == true)
         {
            do
            {
               userGuess = JOptionPane.showInputDialog(null,
                  "I'm thinking of a number between 1 and 1000."
                  +"\nEnter your guess:", "Guessing Game",
                  JOptionPane.QUESTION_MESSAGE);
               guessNum = Integer.parseInt(userGuess);
               if(guessNum != randomNum)
                  if(guessNum < randomNum)
                     JOptionPane.showMessageDialog(null, "Sorry you guessed too low");
                  else
                     JOptionPane.showMessageDialog(null, "Sorry you guessed too high");
               if(guessNum == randomNum)
                  correct = true;

                  ++guessCount;
            }while(guessNum != randomNum);

            if(correct == true)
                  JOptionPane.showMessageDialog(null, "CONGRATULATIONS!"
                     +"\nYou guessed correctly!"
                     +"\nAnd it only took "+guessCount+" tries.");

            Scanner input = new Scanner(System.in);      
            System.out.print("Want to play again? Enter yes or no >> ");
            playAgain = input.nextLine().toUpperCase();

            if(playAgain.equals("NO"))
               startGame = false;
            else
               startGame = true;
         }

   }
   public static boolean launchGame()
   {
      int letsPlay;
      boolean startGame;
      letsPlay = JOptionPane.showConfirmDialog(null,
         "Want to play a guessing game?");
      startGame = (letsPlay == JOptionPane.YES_OPTION);
      System.out.println("startGame is "+startGame);
      return startGame;
   }

}

Answer 1

你可以去掉

if(launchGame() == true)
   startGame = true;

完全，也许使用这个:

boolean startGame = launchGame();             
while(startGame)
             {
                do
                {
                   userGuess = JOptionPane.showInputDialog(null,
                      "I'm thinking of a number between 1 and 1000."
                      +"\nEnter your guess:", "Guessing Game",
                      JOptionPane.QUESTION_MESSAGE);
                   guessNum = Integer.parseInt(userGuess);

另一个潜在的结构改进可能是使用游戏的自然 if else 结构。 “如果猜错了，告诉他们更低或更高，否则告诉他们他们赢了并提议再次玩”这似乎真的是游戏应该做的。

此外，您的正确 boolean 值有点多余，因为要退出循环，正确必须为真，因此您无需再次检查是否正确。

所以:

                  if(guessNum < randomNum)
                     JOptionPane.showMessageDialog(null, "Sorry you guessed too low");
                  else
                     JOptionPane.showMessageDialog(null, "Sorry you guessed too high");
                  ++guessCount;
            }while(guessNum != randomNum);

            JOptionPane.showMessageDialog(null, "CONGRATULATIONS!"
                     +"\nYou guessed correctly!"
                     +"\nAnd it only took "+guessCount+" tries.");

您可能要考虑的最后一件事，也是最基于偏好的事情，是您可能想要以不同方式检查是或否。通常当我看到这类检查时，通常会看到人们获取字符串响应的第一个字母，然后执行 charAt(0)，如果 charAt(0) == 'y' 或 charAt(0) == 'Y '，然后再玩一次，否则你就没有了。如果您更喜欢这种方法，请深思。