java在while循环中遇到问题，并试图通过按字母来终止程序

Question

我的程序有问题

该程序是一个HILO游戏，要求用户在生成的数字范围内猜测一个数字

问题是，一旦我在键盘上按0，它就会显示随机数，基本上必须结束循环并询问用户是想继续还是结束程序。相反，它继续循环，每当我按下键盘上的一个字母时，它就会显示一个Exception错误，该错误描述并输入未匹配。有人能告诉我怎么修吗？，也许我把程序写错了，我尝试了多种方法，但它仍然不能正常工作。 多谢各位

import java.util.Scanner;
import java.util.Random;
import java.lang.Math;

public class HILOGAME
{
    public static void firstGame()
    {
        final int range = 50;
        int answer = 0;
        int guesses;
        int number;
        int guessNum = 0;

        String choice = "";
        boolean Loop = false;

        Scanner input = new Scanner(System.in);
        Random r = new Random();

        answer = r.nextInt(range) + 1;

        System.out.println("IF YOU WISH TO GIVE UP, PRESS 0 ON THE KEYBOARD");

        while (!Loop)
        {
            for (int exit = 0; exit < 10; exit++)
            {
                System.out.print("Guess a number between 1 and " + range + " : ");
                number = input.nextInt();
                guessNum = guessNum++;
                guessNum += 1;

                if (number == answer)
                {
                    System.out.println(" Your guess was correct ");
                    System.out.println();
                    System.out.println("The number was: " + answer);
                    System.out.println("You guess the number with: " + guessNum + " guesses ");
                    System.out.println();
                    System.out.println("Enter x to continue to play or y to endgame");
                    choice = input.nextLine();

                    if (!choice.equalsIgnoreCase("x"))
                    {
                        Loop = true;
                        answer = r.nextInt(range) + 1;
                        System.out.print("A new number");
                        break;
                    }

                    else if (choice.equalsIgnoreCase("y"))
                    {
                        Loop = false;
                        System.out.print("END OF GAME");
                        exit = 11;
                    }
                }

                if (number > answer)
                {
                    System.out.println("TOO HIGH");
                }
                if (number < answer)
                {
                    System.out.println("TOO LOW");
                }

                if (number == 0)
                {
                    System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
                    System.out.println("Enter x to continue to play or y to endgame");
                }

            }
        }
    }
}

Answer 1

编辑1:

这段代码非常适合我，我试过运行它：

final int range = 50;
    int answer = 0;
    int guesses;
    int number;
    int guessNum = 0;

    String choice = "";
    boolean Loop = false;

    Scanner input = new Scanner(System.in);
    Random r = new Random();

    answer = r.nextInt(range) + 1;

    System.out.println("IF YOU WISH TO GIVE UP, PRESS 0 ON THE KEYBOARD");

    while (!Loop)
    {
        int exit;
        for (exit = 0; exit < 10; exit++)
        {
            System.out.print("Guess a number between 1 and " + range + " : ");
            number = input.nextInt();
            guessNum = guessNum++;
            guessNum += 1;

            if (number == answer)
            {
                System.out.println(" Your guess was correct ");
                System.out.println();
                System.out.println("The number was: " + answer);
                System.out.println("You guess the number with: " + guessNum + " guesses ");
                System.out.println();
                System.out.println("Enter x to continue to play or y to endgame");
                choice = input.next();

                // HERE YOU ARE DOING THE WRONG THING
                // What is the meaning of "not(!)" here ? !choice.equalsIgnoreCase("x")
                // Remove "NOT(!)" from here your program will work as expected

                if (choice.equalsIgnoreCase("x"))
                {
                    //here you should assign loop to false if they continue
                    Loop = false;
                    answer = r.nextInt(range) + 1;
                    System.out.print("A new number");
                    break;
                }
                else if (choice.equalsIgnoreCase("y"))
                {
                    //better to insert break here as well
                    //here you should assign loop to true if they wanna exit.
                    Loop = true;
                    System.out.print("END OF GAME");
                    exit = 11;
                    break;
                }
            }

            else if (number > answer)
            {
                System.out.println("TOO HIGH");
            }
            else if (number < answer)
            {
                System.out.println("TOO LOW");
            }

            if (number == 0)
            {
                System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
                System.out.println("Enter x to continue to play or y to endgame");

                // MADE CHANGES HERE

                choice = input.next();

                if (choice.equalsIgnoreCase("x"))
                {
                    //here you should assign loop to false if they continue
                    Loop = false;
                    answer = r.nextInt(range) + 1;
                    System.out.print("A new number");
                    break;
                }
                else if (choice.equalsIgnoreCase("y"))
                {
                    //better to insert break here as well
                    //here you should assign loop to true if they wanna exit.
                    Loop = true;
                    System.out.print("END OF GAME");
                    exit = 11;
                    break;
                }
            }

        }
    }

请复制粘贴代码。因为它毫无例外地工作得很好

我的示例输出：

示例1:

Guess a number between 1 and 50 : 1
TOO LOW
Guess a number between 1 and 50 : 0
TOO LOW
YOU GAVE UP. THE NUMBER WAS 27
Enter x to continue to play or y to endgame
y
END OF GAME

样本2:

Guess a number between 1 and 50 : 20
TOO HIGH
Guess a number between 1 and 50 : 19
TOO HIGH
Guess a number between 1 and 50 : 15
 Your guess was correct 

The number was: 15
You guess the number with: 3 guesses 

Enter x to continue to play or y to endgame
x
A new numberGuess a number between 1 and 50 : 20
TOO LOW
Guess a number between 1 and 50 : 0
TOO LOW
YOU GAVE UP. THE NUMBER WAS 42
Enter x to continue to play or y to endgame
y
END OF GAME

如果有什么问题一定要告诉我

Answer 2

小小的修改

public class HILOGAME {
    public static void firstGame() {
        final int range = 50;
        int answer;
        int number;
        int guessNum = 0;

        String choice = "";
        Scanner input = new Scanner(System.in);
        Random r = new Random();

        answer = r.nextInt(range) + 1;

        System.out.print("Guess a number between 1 and " + range + " : ");
        number = input.nextInt();
        if (number == answer) {
            System.out.println(" Your guess was correct ");
            System.out.println();
            System.out.println("The number was: " + answer);
            System.out.println("You guess the number with: " + guessNum + " guesses ");
            System.out.println();
        } else {
            System.out.println("you entered a wrong value");
            System.out.println("do you really want to try again? press y to continue or other alphabet to exit");
            choice = input.next();
            playAgain(choice);
        }

    }

    public static void playAgain(String choice) {
        if (choice.equalsIgnoreCase("Y")) {
            firstGame();
        } else {
            System.out.println("you chose to quit");
            System.exit(0);
        }
    }

Answer 3

如果你想结束一个循环，你可以使用break;命令。它跳出while或for循环。如果数字是0，你可以用这个：

if (number == 0)
{
  System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
  System.out.println("Enter 'x' to continue to play or y to endgame");
  choice = input.nextLine();
  if(choice == "y")
  {
    break;
  }

并加上： if(choice == "y") {break;}到while(!Loop)循环的最末端

当答案正确时，将Loop设置为false，这意味着!Loop将计算为true。当他们决定继续游戏时，你应该将Loop = false改为Loop = true