Java程序未将对象添加到ArrayList

Question

我正在尝试将不同的对象添加到ArrayList并且不起作用。 我不确定这是因为我添加的对象不正确还是有其他问题。

这是我的代码。

import java.util.*;
import java.io.*;

public class QuizBowl implements Quiz {  
   private Player player;     // player object
   private String file;       // name of file
   private int qNum;          // number of questions player wants to answer
   private int qNumFile;      // number of questions in file
   private ArrayList<Question> questionsArr; // holds Question objects
   private boolean questionsAsked[]; // array of questions that were already asked



   // Constructor
   public QuizBowl(String fName, String lName, String file) throws FileNotFoundException {
      player = new Player(fName, lName);
      Scanner gameFile = new Scanner(new File(file));
      qNum = numOfQuestionsToPlay();
      qNumFile = maxNumQFile(gameFile);
      questionsArr = new ArrayList<Question>();
      readFile();
      System.out.println(questionsArr);
      questionsAsked = new boolean[qNumFile];     
      System.out.println(Arrays.toString(questionsAsked));
   }

   // asks user how many questions to ask
   public int numOfQuestionsToPlay() {
      Scanner console = new Scanner(System.in); 

      // CHECKS FOR VALID USER INPUT
      boolean check = false;
      do {
           try {
               System.out.print("How many questions would you like (out of 3)? ");
               int answer = console.nextInt();
               if(answer > 3) {
                  System.out.println("Sorry, that is too many.");
                  check = false;
               }               
               else {
                  check = true;        
               }              
           }
            catch(InputMismatchException e) {
               System.out.println("Invalid input. Please try again.");
               console.nextLine(); 
               check = false;  
            }
       }
       while(check == false);
       return qNum; 
   }

   // figures out how many questions are in the file 
   public int maxNumQFile(Scanner gameFile) {
      int num = gameFile.nextInt();
      return num;   
   }

   // LOOP FOR READING QUESTIONS    
   public void readFile() {
       for(int i = 0; i < qNum; i++) {
           readQuestion();
       }
   }

    // READS QUESTION AFTER QUESTION AND ADDS TO THE ARRAYLIST OF QUESTIONS OBJECTS
    public void readQuestion() {
        Scanner console = new Scanner(System.in);
        console.nextLine();
        String[] line;
        String question, questionType;
        int points;

        line = console.nextLine().split(" "); 

        questionType = line[0];  
        points = Integer.parseInt(line[1]);  
        question = console.nextLine();

        if(questionType.equals("MC")) {      // checks if question type is MC
            questionsArr.add(readMC(questionType, question, points, console));               // adds MC question to array
        }
        else if(questionType.equals("SA")) { // checks if question type is SA                    
            questionsArr.add(readSA(questionType, question, points, console));               // adds SA question to array           
        }
        else {                                        // checks if question type is TF
            questionsArr.add(readTF(questionType, question, points, console));               // adds TF question to array
        }
    }

    // READS ONE TF QUESTION
    public static QuestionTF readTF(String questionType, String question, int points, Scanner console) {                      // returns new QuestionTF object
        String ans = console.nextLine();
        return new QuestionTF(question, questionType, points, ans);
    }

    // READS ONE SA QUESTION
    public static QuestionSA readSA(String questionType, String question, int points, Scanner console) {
        String ans = console.nextLine();
        return new QuestionSA(question, questionType, points, ans);                        // returns new QuestionSA object
    }

    // READS ONE MC QUESTION
    public static QuestionMC readMC(String questionType, String question, int points, Scanner console) {
        int numChoices;
        String[] choices;
        String ans;
        numChoices = Integer.parseInt(console.nextLine());
        choices = new String[numChoices];
        ans = console.nextLine();

        for(int i = 0; i < numChoices ; i++) {
            choices[i] = console.nextLine();
        }

        return new QuestionMC(question, questionType, points, choices, ans);  // returns new QuestionMC object
    }

    // STARTS QUIZ
    public void quiz() {
        int qCount = 0;
        int ranQ;
        Scanner userInput = new Scanner(System.in);
        String userAns;

        Random r = new Random();

        // RUNS QUIZ 
        while (qCount < qNum) {
            ranQ = r.nextInt(qNumFile);

            // CHECKS IF QUESTION HAS ALREADY BEEN ASKED
            if (!checkDup(ranQ, questionsAsked)) {
                questionsAsked[ranQ] = true;
                Question question = questionsArr.get(ranQ); // GETS RANDOM QUESTION FROM ARRAY
                question.printQuestion();    // prints question and points
                userAns = userInput.next();  // retrieves answer from user
                // CHECKS USER'S ANSWER
                if(userAns.equals("SKIP")) {
                    System.out.println("You have chosen to skip this question.");
                }
                else {
                    checkAnswer(userAns, question, player);
               }

               qCount++;
               System.out.println();
            }
        }
    }

    // CHECKS IF QUESTION HAS ALREADY BEEN ASKED
    public boolean checkDup(int ranQ, boolean questionsAsked[]){
        return questionsAsked[ranQ];
    }


    // CHECKS ANSWER AND ADDS POINTS
    public void checkAnswer(String userAnswer, Question question, Player player) {
        if(question.checkAnswer(userAnswer)) {
            System.out.println("Correct you get " + question.getPoints());
            player.setScore(question.getPoints());
        }
        else {
            System.out.println("Incorrect, the answer was " + question.getAnswer() + "." + 
            " you lose " + question.getPoints() + ".");
            player.setScore(question.getPoints() * -1);
        }
    }

   // Executes program
   public static void main(String[] args) throws FileNotFoundException {     
      Scanner console = new Scanner(System.in);
      System.out.print("Please enter your first name: ");
      String first = console.next();
      System.out.print("Please enter your last name: ");
      String last = console.next();     
      System.out.print("Please enter the game file name: ");
      String file = console.next();

      QuizBowlRedo newGame = new QuizBowlRedo(first, last, file);    // creates new game of QuizBowl
      newGame.quiz();                                                // starts game
   } 
}

这是我的一个对象类的构造函数。 QuestionMC，QuestionSA和QuestionTF扩展了Question类：

public QuestionSA(String question, String questionType, int points, String answer) {
      super(question, questionType, points);
      this.answer = answer;
   }

这是我正在读取的文本文件：

3 
TF 5
There exist birds that can not fly. (true/false) 
true 
MC 10 
Who was the president of the USA in 1991? 
6 
Richard Nixon 
Gerald Ford 
Jimmy Carter 
Ronald Reagan 
George Bush Sr. 
Bill Clinton 
E 
SA 20 
What city hosted the 2004 Summer Olympics? 
Athens

我正在谈论的部分从readQuestion()方法开始。 我正在尝试将对象添加到ArrayList区域中，并带有注释：“读取一个....问题”。 到目前为止，它带有一个空的ArrayList 。

Answer 1

1. readFile()一直循环到qnum并调用readQuestion() 。 但是，它不会将“当前”问题编号传递给readQuestion() 。 所以readQuestion()总是从第一个开始？

2. readQuestion()正在打开输入文件（因此，可能会一遍又一遍地读取第一个问题）。 这可能是readFile()的任务

3. 该方法的第一行从stdin读取。 您可能想从gameFile扫描仪中读取内容？