java在一个问题被连续正确回答三次/并添加差异后，我如何将程序循环回开始

Question

我正在创建一个程序来帮助学生解决y=m（x）+b。现在，我有一个程序来显示菜单，并评估你的回答是否正确。然而，我需要它来计算一行中正确答案的数量

• 如果3次正确，则结束程序并输出总正确的尝试次数
• 否则，如果有3次尝试，则输出为提示

我面临的主要问题是这两种方法的循环。如果我的代码糟糕透顶，我提前道歉，与Python相比，我很难理解其中的方法和类。任何人的建议或提示都会非常有用

到目前为止，我已经尝试添加方法，并尝试将类添加到程序的某些部分，例如

public static void user_input(int point_of_line_cross, int slope, int y_intercept, int independent_variable) {}

及

public static test_input() {}

然而，现在我面临范围界定问题以及引用某些变量的错误

package algebra_Tutor;
import java.util.Scanner;
class AlgebraTutor {

public static void main(String[] args){
    System.out.println("Enter 1 if you would like to solve for Y?");
    System.out.println("Enter 2 if you would like to solve for M?");
    System.out.println("Enter 3 if you would like to solve for B?");
    System.out.println("Enter 4 to Quit");


    //Asks for user input
    System.out.print("Enter your selection: ");
    }

    //Creates random # for values in formula
    int y_ = point_of_line_cross;
    int m_ = slope;
    int b_ = y_intercept; 
    int x_ = independent_variable;

public static void user_input(int point_of_line_cross, int slope, int y_intercept, int independent_variable) {

            // Creates scanner for input of menu Def as menu selector
    Scanner user_Selection = new Scanner(System.in);

            //Converts user input to an integer
    int selection = user_Selection.nextInt();
    user_Selection.close();

    y_intercept = (int) (Math.floor(Math.random() * 201) - 100);
    slope = (int) Math.floor(Math.random() * 201) - 100;
    point_of_line_cross = (int) Math.floor(Math.random() * 201) - 100;
    independent_variable = (int) Math.floor(Math.random() * 201) - 100;

            //Tests what user input was, with expected output
    if (selection  == (1)) {
        System.out.println("You chose to solve for Y: ");
        System.out.println("Y = " +slope +"("+independent_variable+")"+" + "+y_intercept);
        System.out.println("Input your answer: ");
        }
    else if (selection == (2)) {
        System.out.println("You chose to solve for M: ");
        System.out.println("M = "+"("+point_of_line_cross+" - "+y_intercept+")"+" / "+independent_variable);
        System.out.println("Input your answer: ");
        }
    else if (selection == (3)) {
        System.out.println("You chose to solve for B: ");
        System.out.println("B = "+point_of_line_cross+" - "+slope+"("+independent_variable+")");
        System.out.println("Input your answer: ");
        }
    else if (selection == (4)) {
        System.out.println("You chose to quit the program. ");
    return;
        }
        }

//Solves the problem in order to compare to User input
    int answer_y = ((m_) * (x_)) + (b_);
    int answer_m =(y_) - ((b_) / (x_));
    int answer_b =(y_) - ((m_)* (x_));
public static test_input() {
        //Problem solver defined
    Scanner answer_input = new Scanner(System.in);
    int answer = answer_input.nextInt(); 
        //Creates loop for program
    var counter = 0;
    int correct = 0;
    var answers_correct = false;
    while (!answers_correct && correct < 3) {
        if (answer == answer_y){
            counter++;
            correct++;
            System.out.println("You answered correctly");
        return;
        }
        else if (counter >= 3 && correct < 3) {
            System.out.println("Youve been missing the questions lately, let me help! ");
        }
        else
        {
            System.out.println("Try again");
            counter++;
            correct = 0;
        break;
            }
        }
    }
}

我希望在用户连续完成3个问题后，程序能够输出正确的答案。此外，它需要在3次尝试后输出提示。然后在3次修正后，它应该循环回到程序的开头

Answer 1

周六我做代数已经很晚了，所以我会坚持建议修改你的程序结构。首先，你可以通过一个包含问题的类来完成所有事情，并为用户打分。该类中的方法可以通过主菜单中的菜单进行选择。 我写了一个基于标准Java OOP方法的示例，说明了我将如何构建这个框架。在我的程序中，main不需要静态类，它循环一个菜单，并在那里选择一个问题。我的方法只有一个问题，你可以在菜单中随意添加，重要的是结构

 import java.util.Scanner;

//This class contains the two methods and over-all score
class Material {
private int score;
//The user chooses this or the earth method
public void sky() {

    String answer = "null"; 
    int count = 0;
    Scanner input = new Scanner(System.in);
   //within the method, is this while loop which gives a hint after 3 attempts.
    while (!answer.equals("blue") && (!answer.equals("exit"))) {
        System.out.println("What color is the sky? 'exit' to exit");
        answer = input.nextLine();
        count++;
        if (count == 3)
            System.out.println("Hint: It starts with a 'b'");
    }

    if (answer.equals("blue"))
        score += 1;//The score will increment if the choice is correct,
    else//or else leave with nothing...
        return;
}

    //This method is the same as the sky() method, just different question and answer.
public void earth() {

    String answer = "null";
    int count = 0;
    Scanner input = new Scanner(System.in);

    while (!answer.equals("iron") && (!answer.equals("exit"))) {
        System.out.println("What is the core made of? 'exit' to exit");
        answer = input.nextLine();
        count++;
        if (count == 3)
            System.out.println("Hint: It starts with a 'i'");
    }

    if (answer.equals("iron"))
        score += 1;
    else
        return;

}

public int getScore() {
    return score;
}

}

public class Questions {

public static void main(String[] args) {
    //No static methods needed, here is an instance of our test materia class.
    Material material = new Material();

    //The choice and scanner are instantiated here.
    int choice = 0;
    Scanner input = new Scanner(System.in);

    //This while loop uses a switch statement to choose the methods for the questions
    while (choice != 3) {

        if (material.getScore() == 3) {
            System.out.println("Good job, you scored three right.");
            return;
        }

        System.out.println("SCORE: " + material.getScore());
        System.out.println("Anwer questions about the sky: 1");
        System.out.println("Answer quetions about the earth: 2");
        System.out.println("Exit: 3");
        choice = input.nextInt();
       //choices are 1 , 2 for questions, and 3 to leave.
        switch (choice) {
        case 1:
            material.sky();
            break;
        case 2:
            material.earth();
            break;
        case 3:
            System.out.println("Exiting...");
            break;
        default:
            System.out.println("not a valid number choice...");

        }
    }

}// main
}// class

Answer 2

旁注：与要求用户输入1、2、3或4不同，您应该直接要求他们输入他们想要求解的变量：

Solve the equation y = m * x + b for which variable (y, m, b, quit)?

这使得程序的用户更多地考虑问题领域，而不是一些技术上无用的间接方法

---

由于你有Python的背景，你应该知道行的缩进很重要，而且有意义。Java程序也是如此。唯一的区别是Java编译器完全忽略缩进。但是Java程序也可以被人类阅读，对他们来说，缩进对于理解程序的结构是可行的。你发布的代码有不一致的缩进，你应该让IDE来解决这个问题

---

你的程序应该是这样的：

public class AlgebraTutor {

    private final Scanner in = new Scanner(System.in);
    private final PrintStream out = System.out;

    private int attempts = 0;

    void solveForY() {
        ...
    }

    void solveForM() {
        ...
    }

    void solveForB() {
        ...
    }

    void mainMenu() {
        while (true) {
            out.println("Solve the equation y = m * x + b for which variable (y, m, b), or quit?");
            if (!in.hasNextLine()) {
                return;
            }

            switch (in.nextLine()) {
            case "y":
                solveForY();
                break;

            case "m":
                solveForX();
                break;

            case "b":
                solveForB();
                break;

            case "q":
            case "quit":
                return;
            }
        }
    }

    public static void main(String[] args) {
        new AlgebraTutor().mainLoop();
    }
}

Answer 3

我想我会让你自己想办法让它循环，但我解决了你的其他问题，并把评论放在我改变的地方。希望这有帮助

//declared variables here. global variables must be declared static when accessed in a static method (ex: user_input())
static int y_;
static int m_;
static int b_;
static int x_;

public static void main(String[] args) {
    // Creates scanner for input of menu Def as menu selector
    Scanner user_Selection = new Scanner(System.in);

    System.out.println("Enter 1 if you would like to solve for Y?");
    System.out.println("Enter 2 if you would like to solve for M?");
    System.out.println("Enter 3 if you would like to solve for B?");
    System.out.println("Enter 4 to Quit");

    //Converts user input to an integer
    int selection = user_Selection.nextInt();

    //call user_input()
    user_input(selection);


}

public static void user_input(int selection) {

    Scanner user_Selection = new Scanner(System.in);
    int userAnswer;
    int y_intercept = (int) (Math.floor(Math.random() * 201) - 100);
    int slope = (int) Math.floor(Math.random() * 201) - 100;
    int point_of_line_cross = (int) Math.floor(Math.random() * 201) - 100;
    int independent_variable = (int) Math.floor(Math.random() * 201) - 100;

    y_ = point_of_line_cross;
    m_ = slope;
    b_ = y_intercept;
    x_ = independent_variable;


    //Tests what user input was, with expected output
    if (selection == (1)) {
        System.out.println("You chose to solve for Y: ");
        System.out.println("Y = " + slope + "(" + independent_variable + ")" + " + " + y_intercept);
        System.out.println("Input your answer: ");
        userAnswer = user_Selection.nextInt();
        /*After user enters answer we test the answer by calling test_input
         * */
       test_input(userAnswer);
    } else if (selection == (2)) {
        System.out.println("You chose to solve for M: ");
        System.out.println("M = " + "(" + point_of_line_cross + " - " + y_intercept + ")" + " / " + independent_variable);
        System.out.println("Input your answer: ");
        userAnswer = user_Selection.nextInt();
        /*After user enters answer we test the answer by calling test_input
         * */
        test_input(userAnswer);
    } else if (selection == (3)) {
        System.out.println("You chose to solve for B: ");
        System.out.println("B = " + point_of_line_cross + " - " + slope + "(" + independent_variable + ")");
        System.out.println("Input your answer: ");
        userAnswer = user_Selection.nextInt();
        /*After user enters answer we test the answer by calling test_input
         * */
        test_input(userAnswer);
    } else if (selection == (4)) {
        System.out.println("You chose to quit the program. ");
    }
}

// you forgot to include return type ex: void, int, String, double, float, etc
public static void test_input(int entered_answer) {
    //Solves the problem in order to compare to User input
    int answer_y = ((m_) * (x_)) + (b_);
    int answer_m = (y_) - ((b_) / (x_));
    int answer_b = (y_) - ((m_) * (x_));

    //Problem solver defined
    int answer = entered_answer;

    //Creates loop for program
    int counter = 0;
    int correct = 0;
    boolean answers_correct = false;

    while (!answers_correct && correct < 3) {
        if (answer == answer_y) {
            counter++;
            correct++;
            System.out.println("You answered correctly");
            return;
        } else if (counter >= 3 && correct < 3) {
            System.out.println("You've been missing the questions lately, let me help! ");
        } else {
            System.out.println("Try again");
            counter++;
            correct = 0;
            break;
        }
    }

}

`

public static void user_input(int point_of_line_cross, int slope, int y_intercept, int independent_variable)

如果你给了一个方法参数，那么当方法被调用时，你必须自己在参数中输入值。我不认为这是你想要的，因为你定义了你想要的参数值：

y_intercept = (int) (Math.floor(Math.random() * 201) - 100);
slope = (int) Math.floor(Math.random() * 201) - 100;
point_of_line_cross = (int) Math.floor(Math.random() * 201) - 100;
independent_variable = (int) Math.floor(Math.random() * 201) - 100;

在test_input（）方法中，您写道：

Scanner answer_input = new Scanner(System.in);
int answer = answer_input.nextInt();

。nextInt（）将使程序暂停并等待用户输入，以便在准备好获取输入之前不想使用它

我对java中的var关键字了解不多，但我认为与其使用var，不如声明变量类型，因此：

var counter = 0;

为此：

int counter = 0;

为了更好地了解这些方法的工作原理，我推荐以下两个视频： Intro to java methods Java method parameters and return types

要深入了解java的基本原理，我推荐这整张播放列表 Java Beginner Programming