我正在用 Java 制作一個測驗應用程式，并使用 JUnit 來測驗我的方法。現在，我的 src 檔案夾有一個主檔案夾。主檔案夾還有兩個包，模型和 UI。模型包包含一個名為 QuizQuestions 的類，并包含資料建模。UI 包有 2 個類，Quiz 和 Main。Quiz 類為 QuizQuestions 類提供列印陳述句，Main 類具有 Main 方法。這是代碼：
QuizQuestions 類（模型）：
package model;
import ui.Quiz;
import java.util.*;
public class QuizQuestions {
Map<String, String> questionsAndAnswers;
Quiz quiz;
// REQUIRES: the map data structure, specifically the field named questionsAndAnswers
// MODIFIES: nothing
// EFFECTS: creates a new linked hashmap by the name questionsAndAnswers
public QuizQuestions() {
questionsAndAnswers = new LinkedHashMap<>();
}
// REQUIRES: nothing
// MODIFIES: this
// EFFECTS: adds the questions and answers to the linked list in an ordered format
public LinkedHashMap<String, String> entireQuestionsList() {
questionsAndAnswers.put("Purpose of spinning jenny in the Industrial Revolution ",
"\na)A device for making cloth\nb)A device for storing energy\nc)A steam engine\nd)A water pump\n\n");
questionsAndAnswers.put("A city NOT founded by the Romans ", "\na)Alexandria\nb)Berlin\nc)London\nd)None\n\n");
questionsAndAnswers.put("Number of wives Henry VIII had ", "\na)1\nb)6\nc)3\nd)2\n");
questionsAndAnswers.put("Country of origin of Zoroastrianism ", "\na)Brazil\nb)Egypt\nc)Persia\nd)India\n\n");
questionsAndAnswers.put("The person who captured Moscow for the last time in history ",
"\na)No one\nb)Hitler\nc)Napoleon\nd)Ogedei Khan\n\n");
questionsAndAnswers.put("First time the Winter Olympics were held in ",
"\na)1896\nb)1900\nc)1888\nd)1924\n\n");
questionsAndAnswers.put("Number of chapters in the Olympic Charter ", "\na)5\nb)6\nc)7\nd)8\n\n");
questionsAndAnswers.put("Designer of the trophy of FIFA Women’s World Cup? ",
"\na)William Sawaya\nb)Formiga\nc)Marta\nd)Sun Wen\n\n");
questionsAndAnswers.put("The Mission Hills World Cup is related to ", "\na)Golf\nb)Polo\nc)TT\nd)Chess\n\n");
questionsAndAnswers.put("Number of players who have reached the 100-goal mark in EPL ",
"\na)5\nb)10\nc)28\nd)30\n\n");
questionsAndAnswers.put("Location of the Spanish Steps ", "\na)Rome\nb)Lisbon\nc)Madrid\nd)Barcelona\n\n");
questionsAndAnswers.put("Total number of provinces in Canada ", "\na)5\nb)10\nc)30\nd)20\n\n");
questionsAndAnswers.put("A popular Middle Eastern dish ", "\na)Pasta\nb)Dolma\nc)Pizza\nd)Curry\n\n");
questionsAndAnswers.put("Location of the Chocolate Hills ",
"\na)Pakistan\nb)Japan\nc)Philippines\nd)India\n\n");
questionsAndAnswers.put("The tallest building amongst the following is ",
"\na)The Shard\nb)Burj Khalifa\nc)Skytree\nd)Moscow Tower\n\n");
return (LinkedHashMap<String, String>) questionsAndAnswers;
}
// REQUIRES: questionsAndAnswers linked list should not be empty
// MODIFIES: nothing
// EFFECTS: gets the questions and answers from the linked list
// and displays one question and its corresponding answers one after
// the other while providing the user the option to enter his/her answer
// for each question.
public ArrayList<String> askQuestionsOneByOne() {
quiz = new Quiz();
Set<Map.Entry<String, String>> entry = questionsAndAnswers.entrySet();
ArrayList<String> userAnswer = new ArrayList<>();
for (Object o : entry) {
System.out.println(o);
String answer = quiz.askUser();
userAnswer.add(answer);
}
return userAnswer;
}
// REQUIRES: nothing
// MODIFIES: this
// EFFECTS: adds the correct answers of all the questions to
// a linked list and returns that list.
public ArrayList<String> storeCorrectAnswers() {
ArrayList<String> correctAnswers = new ArrayList<>();
correctAnswers.add("a");
correctAnswers.add("a");
correctAnswers.add("b");
correctAnswers.add("c");
correctAnswers.add("c");
correctAnswers.add("d");
correctAnswers.add("b");
correctAnswers.add("a");
correctAnswers.add("a");
correctAnswers.add("d");
correctAnswers.add("a");
correctAnswers.add("b");
correctAnswers.add("b");
correctAnswers.add("c");
correctAnswers.add("b");
return correctAnswers;
}
// REQUIRES: storeCorrectAnswers and askQuestionsOneByOne is not empty
// MODIFIES: nothing
// EFFECTS: stores the answers obtained from storeCorrectAnswers and
// askQuestionsOneByOne into 2 new linked lists and compares both of
// them. Whenever the answer at a particular index in both the lists
// is the same, the score of the user is incremented by 1 and the
// total score is returned at the end of the method.
public int compareAnswers() {
ArrayList<String> userAnswers = storeCorrectAnswers();
ArrayList<String> correctAnswers = askQuestionsOneByOne();
int score = 0;
for (int i = 0; i < userAnswers.size(); i ) {
if (userAnswers.get(i).equals(correctAnswers.get(i))) {
score ;
}
}
return score;
}
// REQUIRES: the value of the score variable from compareAnswers()
// MODIFIES: nothing
// EFFECTS: displays the score of the user and according to the score,
// displays a message informing the user about how good the score is.
public void displayScoreAndPerformanceMessage() {
quiz = new Quiz();
int score = compareAnswers();
quiz.printScore();
if (score < 5 && score > 0) {
quiz.messageForScoreLessThanFive();
askUserToPlayAgain();
} else if (score >= 5 && score < 10) {
quiz.messageForScoreMoreThanFiveAndLessThanTen();
askUserToPlayAgain();
} else if (score >= 10 && score != 15) {
quiz.messageGorScoreMoreThanTenAndLessThanFifteen();
askUserToPlayAgain();
} else {
quiz.messageForPerfectScore();
}
}
// REQUIRES: the list of quiz questions and the user score
// MODIFIES: converts the user answer to lower case if he/she enters
// the response in uppercase.
// EFFECTS: gives the user the option to play the quiz again
// and based on the answer, starts the quiz from scratch or exits the program
public void askUserToPlayAgain() {
quiz = new Quiz();
String response = quiz.askUserForPlayingAgain();
while (response.equalsIgnoreCase("y")) {
entireQuestionsList();
displayScoreAndPerformanceMessage();
askUserToPlayAgain();
}
if (response.equalsIgnoreCase("n")) {
quiz.thankYouMessage();
System.exit(1);
} else {
quiz.errorMessage();
askUserToPlayAgain();
}
}
}
測驗類（UI）：
package ui;
import model.QuizQuestions;
import java.util.Scanner;
public class Quiz {
Quiz qz;
public Quiz() {
qz = new Quiz();
}
public void displayGreeting() {
System.out.println("Welcome to the quiz application!\n\nHere are the quiz questions.");
}
// REQUIRES: nothing
// MODIFIES: nothing
// EFFECTS: allows the user to enter their answer for
// each question and returns that answer.
public String askUser() {
Scanner sc = new Scanner(System.in);
return sc.next();
}
// REQUIRES: score from the compareAnswers method in QuizQuestions
// MODIFIES: nothing
// EFFECTS: displays the score of the user on the screen
public void printScore() {
QuizQuestions qq = new QuizQuestions();
int score = qq.compareAnswers();
System.out.println("Your score is " score);
}
// EFFECTS: displays a particular message if the user score is less than 5
public void messageForScoreLessThanFive() {
System.out.println("Looks like your general knowledge is weak. Try to read books!");
}
// EFFECTS: displays a particular message if the user score is more than 5
// but less than 10.
public void messageForScoreMoreThanFiveAndLessThanTen() {
System.out.println("You are doing good! There is still potential to improve though!");
}
// EFFECTS: displays a particular message if the user score is more than 10
// but less than 15.
public void messageGorScoreMoreThanTenAndLessThanFifteen() {
System.out.println("You are awesome! Your score is better than most of the people!");
}
// EFFECTS: displays a particular message if the user score is equal to 15.
public void messageForPerfectScore() {
System.out.println("Perfect score! Congratulations!");
}
// EFFECTS: asks the user whether he/she wants to play again and prompts them for a response.
public String askUserForPlayingAgain() {
System.out.println("Do you want to play the quiz again? (Y)es/(N)o?\n");
Scanner scanner = new Scanner(System.in);
return scanner.next();
}
// EFFECTS: displays a thank-you message at the end of the program.
public void thankYouMessage() {
System.out.println("Thanks for playing!\n");
}
// EFFECTS: displays an error message if the user does not select a right option
public void errorMessage() {
System.out.println("Please enter a valid response.\n");
}
}
主要方法：
package ui;
import model.QuizQuestions;
public class Main {
public static void main(String[] args) {
QuizQuestions qq = new QuizQuestions();
qq.entireQuestionsList();
qq.askQuestionsOneByOne();
qq.compareAnswers();
qq.displayScoreAndPerformanceMessage();
qq.askUserToPlayAgain();
}
}
我所有的測驗都通過了，但是當我嘗試從 main 方法運行我的程式時，它沒有運行。我哪里錯了？
謝謝
uj5u.com熱心網友回復：
您的代碼存在一些問題。我將在這里總結它們：
- 洗掉 Quiz 類的建構式中的 qz = new Quiz() 行，這導致堆疊溢位，因為它一次又一次地運行建構式。
- 您代碼中的另一個主要問題是，它沒有保存列印和其他用途的分數值，而是不斷初始化新的測驗并在這些新實體中運行 compareAnswers()。您需要在測驗類中保存分數值，并使用該存盤值。
- 最后，在 askQuestionsOneByOne() 中，您將回傳用戶答案，但從不使用它們。相反，在 compareAnswers() 中，您再次初始化新串列。
您可以通過添加分數欄位來修復測驗類（下面的第一個代碼示例）。然后，在主類中，當您運行回傳分數的 compareAnswers() 時，將其保存到當前測驗（下面的第二個代碼示例）。隨后，當您需要分數時，例如在 displayScoreAndPerformance() 呼叫中，從測驗物件中檢索它。Quiz 物件中的 printScore() 也是如此。為此，您需要為 QuizQuestions 中的 Quiz 物件添加 getter 和 setter。
最后，您需要引數化 compareAnswers 以接受用戶的答案，并在 main 方法中將 askQuestionsOneByOne() 的結果傳遞給 compareAnswers()。
public class Quiz {
int score;
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
public class Main {
public static void main(String[] args) {
ArrayList<String> userAnswers = new ArrayList<>();
QuizQuestions qq = new QuizQuestions();
qq.entireQuestionsList();
userAnswers = qq.askQuestionsOneByOne();
qq.getQuiz().setScore(qq.compareAnswers(userAnswers));
qq.displayScoreAndPerformanceMessage();
qq.askUserToPlayAgain();
}
}
public void displayScoreAndPerformanceMessage() {
// quiz = new Quiz();
//int score = compareAnswers();
int score = quiz.getScore();
quiz.printScore();
if (score < 5 && score > 0) {
quiz.messageForScoreLessThanFive();
askUserToPlayAgain();
} else if (score >= 5 && score < 10) {
quiz.messageForScoreMoreThanFiveAndLessThanTen();
askUserToPlayAgain();
} else if (score >= 10 && score != 15) {
quiz.messageGorScoreMoreThanTenAndLessThanFifteen();
askUserToPlayAgain();
} else {
quiz.messageForPerfectScore();
}
}
public void printScore() {
// QuizQuestions qq = new QuizQuestions();
// int score = qq.compareAnswers();
System.out.println("Your score is " score);
}
public class QuizQuestions {
Map<String, String> questionsAndAnswers;
Quiz quiz;
public Quiz getQuiz() {
return quiz;
}
public void setQuiz(Quiz quiz) {
this.quiz = quiz;
}
public int compareAnswers(ArrayList<String> userAnswers) {
ArrayList<String> correctAnswers = storeCorrectAnswers();
int score = 0;
for (int i = 0; i < userAnswers.size(); i ) {
if (userAnswers.get(i).equals(correctAnswers.get(i))) {
score ;
}
}
return score;
}
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