Question

由于父类没有“answer”变量而子类具有私有的“answer”变量，因此我一直在为我的 Java 项目苦苦挣扎。即使父类中有getAnswer方法，UML图的父类中也没有answer变量。任何建议都非常感谢

这是连接父类及其子类的java文件。子类中唯一的东西是构造函数，而父类只有一个构造函数和 2 个 getter。

import java.util.ArrayList;
import java.util.Random;
/**
 *
 * @author Admin
 */


public class SimpleQuiz {
    private ArrayList<Question> myQuestions;
    private int currentQuestion;
    
    public SimpleQuiz()
    {
        myQuestions =new ArrayList<Question>();
        
        myQuestions.add(new ShortAnswerQuestion("1. What is the color of apple?","Red"));
        myQuestions.add(new ShortAnswerQuestion("2. What is my favorite food?","Bacon"));
        myQuestions.add(new FillinBlankQuestion("3. I only have to _____ my head above water one more week","keep"));
        myQuestions.add(new FillinBlankQuestion("4. eight times _____ is equal to fourty","five"));
         myQuestions.add(new TrueFalseQuestion("5. Every animal has a tail","False"));
         myQuestions.add(new TrueFalseQuestion("6. A baby has more bones than an average adult","True"));
        
        myQuestions = shuffleList (myQuestions);
        currentQuestion=0;
    }
       
          public String getCurrentQuestion()
        {
            return myQuestions.get(currentQuestion).getQuestion();
        }
        
        
        public String getCurrentAnswer()
        {
            return myQuestions.get(currentQuestion).getAnswer();
        }
        
        
        public boolean checkCurrentAnswer(String answer)
        {
           return myQuestions.get(currentQuestion).checkAnswer(answer);
        }
        
        //Returns true if this quiz has another question
        public boolean hasNext()
        {
            return currentQuestion < myQuestions.size() - 1;
        }
        
        public void next() throws Exception 
        {
            if(currentQuestion == myQuestions.size()-1)
            {
                throw new Exception("There are no more questions.");
            }
            currentQuestion++;
        }
        
        //Shuffle the list
private ArrayList<Question> shuffleList (ArrayList<Question> inputList)
        {
                ArrayList<Question> randomList = new ArrayList<Question>();
                
                Random r=new Random();
                int randomIndex=0;
                while(inputList.size() > 0)
                {
                   randomIndex=r.nextInt(inputList.size());  //Choose a random object in the list
                   randomList.add(inputList.get(randomIndex));   //add it to the new, random list
                   inputList.remove(randomIndex);   //remove to avoid duplicates
                }
                
                return randomList;  //return the new random list
        }
}

Answer 1

问题对我来说不清楚，你有 UML 并且需要在代码中实现确切的定义？

如果是，我认为只有 3 个选项：

父项中缺少字段 answer
Parent 是抽象的，而 getAnswer() 是抽象的方法
在父级实现方法getAnswer()为空，并在子级中覆盖它并返回子级的私有答案

Answer 2

我不确定你从哪里得到了 UML 图，但它可以优化。看问题陈述，问题不应该是一个类，如果不是抽象类，它应该是一个接口，并且不应该有任何实例变量和构造函数。在超类中有一个实例变量“问题”是没有意义的。 Question 超类应该作为一个标记，下面是代码

interface Question{

String getQuestion();

String getAnswer();

boolean checkAnswer(String str);
}

现在实现类需要提供方法的定义。

继承子类私有变量

2 个答案: