Question

我正在尝试为Android做一个简单的测验，

我被告知我应该尝试使用对象引用。

我不太清楚怎么做，这是我到目前为止所做的......

package com.aleksei.etb;
public class ETBetaActivity extends Activity implements View.OnClickListener {

       private String[] questions =
        {"Q1", 
         "Q2",
         "Q3", 
         "Q4",
         "Q5", //5
         "Q6", 
         "Q7", 
         "Q8", 
         "Q9",
         "Q10" //10
         };
         private String[] answers_correct =
        {"Correct answer - 1",
         "Correct answer - 2",
         "Correct answer - 3", 
         "Correct answer - 4",
         "Correct answer - 5",
         "Correct answer - 6",
         "Correct answer - 7",
         "Correct answer - 8",
         "Correct answer - 9",
         "Correct answer - 10"
         };

         private String[][] answers_wrong = 
         { {"Q1-1", "Q1-2" , "Q1-3"},
           {"Q2-1", "Q2-2" , "Q2-3"},
           {"Q3-1", "Q3-2" , "Q3-3"},
           {"Q4-1", "Q4-2" , "Q4-3"},
           {"Q5-1", "Q5-2" , "Q5-3"},
           {"Q6-1", "Q6-2" , "Q6-3"},
           {"Q7-1", "Q7-2" , "Q7-3"},
           {"Q8-1", "Q8-2" , "Q8-3"},
           {"Q9-1", "Q9-2" , "Q9-3"},
           {"Q10-1", "Q10-2" , "Q10-3"}

         };
         private int counter = 0;
         public Button answer_1,
         answer_2,answer_3,
         answer_4,skip;

         public TextView question_tv,
         tip_tv;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        getData();
        quizBegin();
    }

    public static int getResults(){
       return 5;
    }


    @Override
    public void onClick(View view) {
        switch(view.getId()){
        case R.id.button5: //main
            break;
        case R.id.button1: //answer_1
            break;
        case R.id.button2: //answer_2
            break;
        case R.id.button3: //answer_3
            break;
        case R.id.button4: //answer_3
            break;
        }
    }

    private void getData(){
        //Everything
        skip = (Button) findViewById(R.id.button5);
        answer_1 = (Button) findViewById(R.id.button1);
        answer_2 = (Button) findViewById(R.id.button2);
        answer_3 = (Button) findViewById(R.id.button3);
        answer_4 = (Button) findViewById(R.id.button4);
        question_tv = (TextView) findViewById(R.id.question);
        tip_tv = (TextView) findViewById(R.id.answ1);

        //Buttons
        skip.setOnClickListener(this);
        answer_1.setOnClickListener(this);
        answer_2.setOnClickListener(this);
        answer_3.setOnClickListener(this);
        answer_4.setOnClickListener(this);

        //Text
        skip.setText("Begin!");
        answer_4.setText("");
        answer_3.setText("");
        answer_2.setText("");
        answer_1.setText("");
        tip_tv.setText(""); 
    }

    private void quizBegin(){
        String question = Question.(questions[counter], answers_correct[counter],
                answers_wrong[counter],counter); //error here.

        //What am I suppose to do??
            // How to use an object reference??
            // Help please!

        question_tv.setText("");



        counter++;
    }



}

问题类，它封装了一个问题及其正确和错误的答案。

public class Question {

    private String question;
    private String correctAnswer;
    private List<String> incorrectAnswers;
    private int counter = 0;



    public Question(final String question, final String correctAnswer, 
            final String[] incorrectAnswers, int counter) {
    // TODO: empty strings/nulls checks
    this.question = question;
    this.correctAnswer = correctAnswer;
    this.incorrectAnswers = Arrays.asList(incorrectAnswers);
    }

    public List<String> getPossibleAnswers() {
        final List<String> result = new ArrayList<String>();
        result.addAll(incorrectAnswers);
        result.add(correctAnswer);
        Collections.shuffle(result);
        return result;
    }

    public boolean isCorrectAnswer(final String answer) {
        if (answer.equals(correctAnswer)) {
            return true;
        }
        return false;
    }

    public String getQuestion() {
        return question;
    }

}

Answer 1

我只能猜测你的实际问题，但为什么你使用字符串数组来表示问题，答案正确和错误答案？为什么不使用Question个对象数组，如果正确或错误地回答了Question对象，请让它管理。

修改

语句new Question(questions[counter], answers_correct[counter], answers_wrong[counter],counter);调用Question类中的构造函数，该构造函数采用给定的参数的类型，顺序和数量来创建对象的instance。

Question q = new Question();

创建一个新的Question对象实例并分配对变量q的引用，该变量可用于从其引用的Question类的isntance中访问信息。这是面向对象编程的基本概念。

第二次编辑

此行适用于您：

String [] sl =（String []）q_class.getPossibleAnswers（）。toArray（new String [0]）;

但是对String数组的强制转换（(String[])）是没有意义的。方法toArray(T[])使用generics并返回一个与传递给它的数组类型相同的数组。因此，将new String[0]传递给该方法可确保您获得String[]。因此，您要将String[]投射到String[]。

你真的想在第一时间这样做吗？为什么不能使用List<String>代替数组？

如果你要从一个类型到另一个类型进行大量的转换，你应该问自己是否可以调整你的代码来操作单一类型。

（旁注，您可以使用反引号（`）来表示内联代码部分，这有助于保持您在注释中放置的代码片段更容易拉出和读取。）

我该如何使用Java对象引用？

1 个答案: