java - 该条件在 JOptionPane 中如何工作？

Question

我正在尝试制作两个类别的测验程序:Java 或 C++。我想提出一个有 4 个答案的问题(多项选择)，但我不知道条件如何运作以及如何保存用户得分。

应用程序使用 JOptionPane 与用户交互。

这是我到目前为止所拥有的:

import javax.swing.JOptionPane;

public class Quiz1
{
    public static void main(String[] args) 
    {
        int score = 0;
        JOptionPane.showMessageDialog(null,"WELCOME");
        String name = JOptionPane.showInputDialog(null,"Enter Your Name: ");

        String [] Intro = new String [] {"JAVA","C++"};
        int option = JOptionPane.showOptionDialog(null, "Choose a Category" , "Menu", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE, null,  Intro, Intro[0]);


        if (option == JOptionPane.YES_OPTION) // I just make YES or NO option since there are 2 choices
        {
            JOptionPane.showMessageDialog(null, "Hello "+ name + "\n Welcome to Java Quiz!");
            JOptionPane.showMessageDialog(null, "1. Please read the questions carefully \n 2. Answer all the question \n 3. Scores will be computed after the quiz \n 4. No Cheating!","RULES",JOptionPane.WARNING_MESSAGE);
            JOptionPane.showMessageDialog(null, "This Quiz consist of \n 1. Multiple Choice \n 2.Enumeration \n 3. True/False");
            JOptionPane.showMessageDialog(null,"Quiz #1: Enter the correct letter of the answer");

            // STRING OF QUESTIONS
            String[] quesJava = new String [] {"1) The JDK command to compile a class in the file Test.java is", "2)    Java was developed by_____."};


            String[] answers1 = new String[] {"A) java Test.java", "B) java Test","C) javac Test","D) javac Test.java"};
            int answer1 = JOptionPane.showOptionDialog(null, quesJava[0], "JAVA", JOptionPane.DEFAULT_OPTION, JOptionPane.QUESTION_MESSAGE, null, answer1, answer1[0]);

            if (answer1== ???????????) // the answer is letter "D" but I don't know what will I put in here
            {
                score++;
            }

            String[] answer2 = new String[] {"A) IBM ", "B) Microsoft ","C) Sun Microsystem ","D) Oracle"};
            int answer2 = JOptionPane.showOptionDialog(null, quesJava[1], "JAVA", JOptionPane.DEFAULT_OPTION, JOptionPane.QUESTION_MESSAGE, null, answer2, answer2[0]);
            {
                if (answer2== )
                {
                    score++;
                }
            }
            JOptionPane.showMessageDialog(null,"your score is"+score);
        }
    }
}

Answer 1

我将重写您提供的代码以使这变得稍微容易一些......

这是最终结果:

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

public class Quiz {

    /**
     * This holds all the java questions.
     */
    private static final Question[] JAVA_QUESTIONS = new Question[]{
        new Question("Who developed Java?", 2, "Google", "Sun Microsystems", "Microsoft", "Oracle"),
        //This creates the question: Who developed java with 4 answers (google, Sun, Microsoft and Oracle)
        //The correct answer is 2 (Sun).
        new Question("What modifier is used to make a variable constant?", 3, "public", "abstract", "final", "import")
    };

    /**
     * This holds all the c++ questions.
     */
    private static final Question[] CPP_QUESTIONS = new Question[]{
        new Question("C++ is?", 4, "Interpreted", "A scripting language", "The first programming language", "Compiled")
    };

    /**
     * The users score
     */
    private int score;

    /**
     * The users name
     */
    private String name;

    /**
     * What language the user selected.
     */
    private Language lang;

    private Quiz() {
        setLookAndFeel();//Makes everything look nice
        showOpeningDialogs();//Shows the welcome dialogs
        askQuestions(10);//Asks random questions 10 times depending on what language is selected. 
    }

    /**
     * Asks random questions depending on the language chosen.
     *
     * @param maxScore the number of questions to ask
     */
    private void askQuestions(int maxScore) {
        for (int i = 0; i < maxScore; i++) {
            Question q = getRandomQuestion(lang);//Gets a random question for the language chosen.
            if (ask(q)) {//Checks if they got it correct
                JOptionPane.showMessageDialog(null, "You answered correctly");//Tell them they got it correct
                score++;//Increment their score.
            } else {//If they got it wrong
                JOptionPane.showMessageDialog(null, "You answered incorrectly. The answer is: " + q.getChoices()[q.getCorrectAnswer()]);
                //Tell them they got it wrong and what the correct answer is.
            }
        }

        JOptionPane.showMessageDialog(null, "Your score is: " + score + "/" + maxScore);//At the end, tell them their score
    }

    /**
     * Asks a question and returns whether the player got it correct.
     *
     * @param question
     * @return
     */
    private boolean ask(Question question) {
        //Shows a dialog with the question and answers.
        int choice = JOptionPane.showOptionDialog(
                null,
                question.getQuestion(),
                lang.getDisplayName(),
                JOptionPane.DEFAULT_OPTION,
                JOptionPane.QUESTION_MESSAGE,
                null,
                question.getChoices(),
                question.getChoices()[0]);

        //Checks to see if the answer is correct. This is determined by the answer variable in the question object.
        if (choice == question.getCorrectAnswer()) {
            return true;
        }

        return false;
    }

    /**
     * Just makes everything look nice. You don't have to worry about this.
     */
    private void setLookAndFeel() {
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if (/**What java look and feel*/
                        "Windows".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {
            //Very unlikely to happen
        }
    }

    /**
     * Shows the welcome dialogs and so on.
     */
    private void showOpeningDialogs() {
        name = JOptionPane.showInputDialog(null, "Welcome.\nPlease enter you name:");//Gets the users name.

        String[] langs = new String[]{Language.JAVA.getDisplayName(), Language.CPP.getDisplayName()};
        int opt = JOptionPane.showOptionDialog(null, "Please chose your language", "Menu", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE, null, langs, langs[0]);//Gets the language the user chose.

        //Set the language depending on the users choice.
        switch (opt) {
            case JOptionPane.YES_OPTION:
                lang = Language.JAVA;
                break;
            default:
                lang = Language.CPP;
        }

        //The instructions.
        JOptionPane.showMessageDialog(null, "Hello " + name + "\nWelcome to the " + lang.getDisplayName() + " Quiz!");
        JOptionPane.showMessageDialog(null, "1. Please read the questions carefully \n2. Answer all the question \n3. Scores will be computed after the quiz \n4. No Cheating!", "RULES", JOptionPane.WARNING_MESSAGE);
        JOptionPane.showMessageDialog(null, "This Quiz consist of \n 1. Multiple Choice");

        //Do they want to continue
        int begin = JOptionPane.showOptionDialog(null, "Are you ready to begin?", "Menu", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE, null, new String[]{"Yes", "No"}, "Yes");

        if (begin != JOptionPane.YES_OPTION) {
            System.exit(0);
        }
    }

    /**
     * Gets a random question for a language
     *
     * @param lang the language
     * @return a random question
     */
    private Question getRandomQuestion(Language lang) {
        switch (lang) {
            case JAVA://If the language is java, choose a java question.
                int random = new Random().nextInt(JAVA_QUESTIONS.length);
                return JAVA_QUESTIONS[random];
            case CPP://Else choose a C++ question.
                random = new Random().nextInt(CPP_QUESTIONS.length);
                return CPP_QUESTIONS[random];
        }

        return null;
    }

    public static void main(String[] args) {
        Quiz q = new Quiz();//Just starts the application.
    }

    /**
     * This class holds a question, the correct answer and the choices.
     */
    private static final class Question {

        /**
         * The question being asked
         */
        private final String question;

        /**
         * The correct choice. The index of the choices array.
         */
        private final int correctAnswer;

        /**
         * The 4 choices the player can choose
         */
        private final String[] choices;

        public Question(String question, int correctAnswer, String... choices) {
            if (question == null) {
                throw new NullPointerException("The question cannot be null");
            }

            if (correctAnswer < 1 || correctAnswer > 4) {
                throw new IllegalArgumentException("Correct answer must be between 0 and 5 (1 to 4)");
            }

            if (choices == null) {
                throw new NullPointerException("choices cannot be null");
            }

            if (choices.length != 4) {
                throw new NullPointerException("Choices must have 4 options");
            }

            this.question = question;
            this.correctAnswer = correctAnswer - 1;
            this.choices = choices;
        }

        /**
         * @return the question
         */
        public String getQuestion() {
            return question;
        }

        /**
         * @return the correctAnswer
         */
        public int getCorrectAnswer() {
            return correctAnswer;
        }

        /**
         * @return the choices
         */
        public String[] getChoices() {
            return choices;
        }
    }

    /**
     * Which language we're using
     */
    private enum Language {

        /**
         * The Java programming language
         */
        JAVA("Java"),
        /**
         * The C++ programming language
         */
        CPP("C++");

        //The display name for the language
        private final String displayName;

        Language(String displayName) {
            this.displayName = displayName;
        }

        public String getDisplayName() {
            return displayName;
        }
    }
}

它的作用:根据所选语言随机询问问题。

它是如何做到的:

它首先询问用户:他们的姓名以及他们想要测试的语言。这是在 showOpeningDialogs() 方法中完成的。他们在变量 name 和 lang 中提供的信息。

然后继续提问(重要部分)

在类的最顶部，我们有两个保存问题的数组，一个用于 Java(JAVA_QUESTIONS)，另一个用于 C++(CPP_QUESTIONS)。这些数组保存问题、答案和正确答案。要添加更多问题，您只需向数组中添加一个新问题即可。

调用方法askQuestions(int maxScore)。它首先从方法 getRandomQuestion(Language lang) 获取随机问题，然后调用方法 ask(Question Question)，该方法向用户显示问题并返回用户是否正确。如果他们答对了，score 变量就会递增，并且会出现一个对话框，告诉他们答对了，如果答错了，会出现一个对话框，告诉他们正确的答案。此循环会循环您使用变量 maxScore 指定的次数(这可能应该低于数组中的问题数)。

代码有很好的文档记录，可以指导您完成正在发生的事情。

您需要稍微尝试一下代码才能完全理解它，但在大多数情况下，您想要的东西相当简单。