while 循环从错误的点开始 [Java]

Question

我对 java 很陌生，对 while 循环也很陌生。我的循环有问题，我制作了一个基本的计算器，并在你计算了一些东西之后给了它一个计算其他东西的选项。当出现此选项时，我输入 "Y"（大写）它 "restarts"，但如果我回答 "y"（小写），它会返回到您选择的内容。

例如：如果我启动计算器，我会得到 5 个选项，如果我选择选项 1 并走到最后，我会得到一个选择：如果我想 "try again" 那么如果我选择回答 "Y" 整个事情可以追溯到 "screen" ，在那里我可以选择要做什么。但是当我选择回答 "y" 时，它又回到了我之前选择的那个点。就像我选择选项 1 并回答 "y" 它会回到选项 1.

我试图在网上查找但找不到任何东西，所以要么我不知道使用正确的关键字，要么其他人不经常运行解决我的问题。

这是计算器，里面有一些荷兰语单词，比如计算器或非常糟糕的英语，但 none 无论如何都很重要：

import java.util.*;

public class GEKENMCHINENENE {
    public static void main(String[] args){

        char aga = 'y';
        while(aga == 'y' || aga == 'Y'){
        Scanner antwoord = new Scanner(System.in);
        int aw;

do{

    System.out.println("enter 1 for addition. enter 2 for subtraction. enter 3 for division. enter 4 for multiplication.");
    System.out.println("+------------------------------+");
    System.out.println("|         Calculator           |");
    System.out.println("|------------------------------|");
    System.out.println("|  Press 1 for addition        |");
    System.out.println("|  Press 2 for subtraction     |");
    System.out.println("|  Press 3 for division        |");
    System.out.println("|  Press 4 for multiplication  |");
    System.out.println("|  Press 5 for my social media |");
    System.out.println("|  *credit to creepershelp*    |");
    System.out.println("|        *on pastebin*         |");
    System.out.println("+------------------------------+");


    aw = antwoord.nextInt();

    do{

        if (aw > 5){
            System.out.println("That number is out of range, try aga within the range of 1 - 4");
        aw = antwoord.nextInt();

        }else if(aw < 1){
            System.out.println("That number is out of range, try aga within the range of 1 - 4");
        aw = antwoord.nextInt();
        }else if(aw < -1){
            System.out.println("That number is out of range, try aga within the range of 1 - 4");
        aw = antwoord.nextInt();
        }

        if(aw == 1){
            System.out.println("You choose for 1, addition. Enter your first number.");
        double fnum = antwoord.nextDouble();
            System.out.println("Enter your second number");
        double snum = antwoord.nextDouble();
        double awp = fnum + snum;
            System.out.println("The answer is " + awp);
            System.out.println("Wood you like to reken uit something else? [Y/N]");
            aga = antwoord.next().charAt(0);


            if(aga == 'n'){
                System.out.println("Shutting down...");
            }if(aga == 'n'){
                aga = 'n';
                antwoord.close();
                break;
            }else if(aga == 'N'){
                System.out.println("Shutting down...");
            }if(aga == 'N'){
                aga = 'N';
                antwoord.close();
                break;
            }else if(aga == 'y'){
                System.out.println("Please wait!");
            }else if(aga == 'Y'){
                System.out.println("Please wait!");
            aw = 0;
            }
        }

        if(aw == 2){
            System.out.println("You choose for 2, subtraction. Enter your first number.");
        double fnum = antwoord.nextDouble();
            System.out.println("Enter your second number");
        double snum = antwoord.nextDouble();
        double awp = fnum - snum;
            System.out.println("The answer is " + awp);
            System.out.println("Wood you like to reken uit something else? [Y/N]");
            aga = antwoord.next().charAt(0);


            if(aga == 'n'){
                System.out.println("Shutting down...");
            }if(aga == 'n'){
                aga = 'n';
                antwoord.close();
                break;
            }else if(aga == 'N'){
                System.out.println("Shutting down...");
            }if(aga == 'N'){
                aga = 'N';
                antwoord.close();
                break;
            }else if(aga == 'y'){
                System.out.println("Please wait!");
            }else if(aga == 'Y'){
                System.out.println("Please wait!");
            aw = 0;
            }
        }

        if(aw == 3){
            System.out.println("You choose for 3, division. Enter your first number.");
        double fnum = antwoord.nextDouble();
            System.out.println("Enter your second number");
        double snum = antwoord.nextDouble();
        double awp = fnum / snum;
            System.out.println("The answer is " + awp);
            System.out.println("Wood you like to reken uit something else? [Y/N]");
            aga = antwoord.next().charAt(0);


            if(aga == 'n'){
                System.out.println("Shutting down...");
            }if(aga == 'n'){
                aga = 'n';
                antwoord.close();
                break;
            }else if(aga == 'N'){
                System.out.println("Shutting down...");
            }if(aga == 'N'){
                aga = 'N';
                antwoord.close();
                break;
            }else if(aga == 'y'){
                System.out.println("Please wait!");
            }else if(aga == 'Y'){
                System.out.println("Please wait!");
            aw = 0;
            }
        }

        if(aw == 4){
            System.out.println("You choose for 4, multiplication. Enter your first number.");
        double fnum = antwoord.nextDouble();
            System.out.println("Enter your second number");
        double snum = antwoord.nextDouble();
        double awp = fnum * snum;
            System.out.println("The answer is " + awp);
            System.out.println("Wood you like to reken uit something else? [Y/N]");
            aga = antwoord.next().charAt(0);


            if(aga == 'n'){
                System.out.println("Shutting down...");
            }if(aga == 'n'){
                aga = 'n';
                antwoord.close();
                break;
            }else if(aga == 'N'){
                System.out.println("Shutting down...");
            }if(aga == 'N'){
                aga = 'N';
                antwoord.close();
                break;
            }else if(aga == 'y'){
                System.out.println("Please wait!");
            }else if(aga == 'Y'){
                System.out.println("Please wait!");
            aw = 0;
            }

        }if(aw == 5){
            System.out.println("Instagram: rubettt, https://www.instagram.com/rubettt/?hl=en");
            System.out.println("Snapchat:  rubet23-1212121");
            System.out.println("Wood you like to reken uit something else? [Y/N]");
            aga = antwoord.next().charAt(0);


            if(aga == 'n'){
                System.out.println("Shutting down...");
            }if(aga == 'n'){
                aga = 'n';
                antwoord.close();
                break;
            }else if(aga == 'N'){
                System.out.println("Shutting down...");
            }if(aga == 'N'){
                aga = 'N';
                antwoord.close();
                break;
            }else if(aga == 'y'){
                System.out.println("Please wait!");
            }else if(aga == 'Y'){
                System.out.println("Please wait!");
            aw = 0;
            }
        }if(aw == 0){
            System.out.println("Succesfully shut down!");
        }else if(aga == 'n' || aga == 'N'){
            System.out.println("Succesfully shut down!");
        }

        }while(aw > 1 && aw <329108321);

        }while(aga == 'y' || aga == 'Y');


        }
    }
}

我试着让它把 "y" 改成 "Y" 但这也没有用。如果有人有任何想法，请帮忙。我很想知道这是为什么以及如何解决它。提前致谢，

-Rubet23

Answer 1

您在检查小写字母时忘记将 aw 设置为 0 'y,' 因此 while 循环重复，因为您从未更改数字。在最底部，您的代码应该是：

//The stuff above this
else if(aga == 'y'){
    System.out.println("Please wait!");
    aw = 0;
}
//The rest of your code`

这与您的问题无关，但我认为您每次都应使用 aga.toUpper() 将输入设为大写。这样您就不必为两种情况编写两次相同的代码；您可以只测试字母的大写实例。

祝你好运！

Answer 2

您有两个循环运行 while(aga == 'y' || aga == 'Y');。两者之间没有区别。如果你想让这两种可能性以两种不同的方式表现，你也需要以两种不同的方式使用它们。

当您将其中一个比较移动到另一个 while 条件时，它似乎应该像您希望的那样运行：

while(aw > 1 && aw <329108321 && aga != 'y');

请注意，您的代码很难阅读，因为您的缩进非常不一致。

Answer 3

注：这不是回答，只是对代码结构的批评

您输入 "yes" 和 "no" 的方式很容易出错，因为您一遍又一遍地重复使用相同的代码。创建一个 returns 布尔值的方法。例如：

/**
 * This method will return true for yes and false for no.
 * It is private, because it is unnecessary for other
 * Classes to use it.
 */
private boolean sayYes(String text){
    Scanner keyboard = new Scanner(System.in);
    while(true){
        System.out.print(text);
        // Gets keyboard input, trims it, and makes it lower case.
        String input = keyboard.nextLine().trim().toLowerCase;
        // Checks for "Yes"
        if(input.equals("y") || input.equals("yes"))
            return true;
        // Checks for "No"
        if(input.equals("n") || input.equals("no"))
            return false;
        // If we got here, then it was neither a "yes" or "no",
        // so we complain, and go around the loop again
        System.out.println("Invalid input.");
    }
    // The keyboard Scanner is not closed so the program can
    // continue to receive keyboard input from other places.
}

然后您可以调用此方法：

if(sayYes("Wood you like to reken uit something else? [Y/N]\n")){
    aw = 0;
} else {
    antwoord.close();
    break;
}

这也让输入系统更加健壮，因为他们可以多次输入响应，并且他们可以在不破坏代码的情况下输入完全乱码。你也可以做一个类似的系统来检索号码。

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