android中如何保证其中一个选择题答案是正确的？

Question

我正在尝试创建多项选择数学题。我设法创建了 4 个随机答案，但我不确定如何输入正确答案。它必须是选项 1、2、3 或 4，并且应该是随机的。

我的java代码：

public class MainActivity extends AppCompatActivity{
private boolean correct;
private String questionTxt, option1String, option2String, option3String, option4String;
private int answer;
TextView option1Text, option2Text, option3Text, option4Text;
int r = (int) (Math.random() * (4 - 1)) + 1;

public void correctAnswer()
{
    int first = (int)(Math.random() * 10);
    int second = (int)(Math.random() * 10);
    answer = first + second;
    questionTxt = first + " + " + second + " = ?";
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);

    /*ImageView rocketImage = (ImageView) findViewById(R.id.img_animation);
    rocketImage.setBackgroundResource(R.drawable.greencartooncar);
    rocketAnimation = (AnimationDrawable) rocketImage.getBackground();*/
    TextView questionText = (TextView)findViewById(R.id.question);
    correctAnswer();
    questionText.setText(questionTxt + "");
    option1Text = (TextView)findViewById(R.id.option1);
    option1Text.setText(wrongAnswer() + "");
    option2Text = (TextView)findViewById(R.id.option2);
    option2Text.setText(wrongAnswer() + "");
    option3Text = (TextView)findViewById(R.id.option3);
    option3Text.setText(wrongAnswer() + "");
    option4Text = (TextView)findViewById(R.id.option4);
    option4Text.setText(wrongAnswer() + "");
    setString();
    if (option1String.equals(option2String)||option1String.equals(option3String)||option1String.equals(option4String)
            ||option2String.equals(option3String)||option2String.equals(option4String)||option3String.equals(option4String))
    {
        noSameAnswer();
    }
}

public int wrongAnswer()
{
    return (int)(Math.random() * 10 + Math.random() * 10);
}

public void onClick3(View v) {
    if (option3String.equals(Integer.toString(answer))) {
        TextView questionText = (TextView) findViewById(R.id.question);
        correctAnswer();
        questionText.setText(questionTxt + "");
        option1Text = (TextView)findViewById(R.id.option1);
        option1Text.setText(wrongAnswer() + "");
        option2Text = (TextView)findViewById(R.id.option2);
        option2Text.setText(wrongAnswer() + "");
        option3Text = (TextView)findViewById(R.id.option3);
        option3Text.setText(wrongAnswer() + "");
        option4Text = (TextView)findViewById(R.id.option4);
        option4Text.setText(wrongAnswer() + "");
        setString();
        noSameAnswer();
    }
}

public void onClick1(View v) {
    if (option1String.equals(Integer.toString(answer))) {
        TextView questionText = (TextView) findViewById(R.id.question);
        correctAnswer();
        questionText.setText(questionTxt + "");
        option1Text = (TextView)findViewById(R.id.option1);
        option1Text.setText(wrongAnswer() + "");
        option2Text = (TextView)findViewById(R.id.option2);
        option2Text.setText(wrongAnswer() + "");
        option3Text = (TextView)findViewById(R.id.option3);
        option3Text.setText(wrongAnswer() + "");
        option4Text = (TextView)findViewById(R.id.option4);
        option4Text.setText(wrongAnswer() + "");
        setString();
        noSameAnswer();
    }
}

public void onClick2(View v) {
    if (option2String.equals(Integer.toString(answer))) {
        TextView questionText = (TextView) findViewById(R.id.question);
        correctAnswer();
        questionText.setText(questionTxt + "");
        option1Text = (TextView)findViewById(R.id.option1);
        option1Text.setText(wrongAnswer() + "");
        option2Text = (TextView)findViewById(R.id.option2);
        option2Text.setText(wrongAnswer() + "");
        option3Text = (TextView)findViewById(R.id.option3);
        option3Text.setText(wrongAnswer() + "");
        option4Text = (TextView)findViewById(R.id.option4);
        option4Text.setText(wrongAnswer() + "");
        setString();
        noSameAnswer();
    }
}

public void onClick4(View v) {
    if (option4String.equals(Integer.toString(answer))) {
        TextView questionText = (TextView) findViewById(R.id.question);
        correctAnswer();
        questionText.setText(questionTxt + "");
        option1Text = (TextView)findViewById(R.id.option1);
        option1Text.setText(wrongAnswer() + "");
        option2Text = (TextView)findViewById(R.id.option2);
        option2Text.setText(wrongAnswer() + "");
        option3Text = (TextView)findViewById(R.id.option3);
        option3Text.setText(wrongAnswer() + "");
        option4Text = (TextView)findViewById(R.id.option4);
        option4Text.setText(wrongAnswer() + "");
        setString();
        noSameAnswer();
    }
}
}

一些不需要的方法被删掉了。 int r 字段是一个从 1 到 4 的随机数，但我不知道如何使用它来使正确答案转到选项 1、2、3 或 4。我希望将正确答案设置为选项（随机数）文本。

Answer 1

     private int fetchCorrectAnswer() {
            int correctAnswer = 4;
            int option = new Random().nextInt(2); // outputs either 0 or 1
            //if option is 1 which is randomly genereted, correctAnswer will be 4. 
            //if option is 0,then correctAnswer will be wither 1 or 2 or 3 which is also randomly generated
            if(option == 0){
              //if 0, then it should be between 1/2/3 i.e min = 1, max = 3
              correctAnswer = (new Random().nextInt(max - min + 1)) + 1; // +1 because 0-2 as 1-3
            }
            return correctAnswer;
     }

Answer 2

如果我答对了你的问题，你想在某个选项中随机放置正确的答案。

您可以使用以下方法来达到同样的效果。

private String[] makeOptions(int correctAns) {

        String [] ansStrins = new String[4];
//        for (int i=0;i<ansStrins.length;i++){
//            System.out.println("Option "+i+ ": "+ansStrins[i]);
//
//        }
        int randomPos = (new Random().nextInt())%4;
        ansStrins[randomPos]=correctAns+"";
        for (int i=0;i<4;i++){
            int randomAns = (int)(Math.random() * 10 + Math.random() * 10);
           if(ansStrins[i]==null){
               ansStrins[i]=randomAns+"";
           }
        }
        return ansStrins;
    }

现在使用该选项数组。

android中如何保证其中一个选择题答案是正确的？

How to guarantee one of the multiple choice answers is correct in android?

java

android

multiple-choice