java - 从数据库加载随机 Qid(问题)？

Question

我想每次加载不同的问题。我尝试了以下代码，但它仅随机更改第一个问题。所有其他问题都按顺序排列。

QuizHelper db = new QuizHelper(this);  // my question bank class
        quesList = db.getAllQuestions();  // this will fetch all quetonall questions
        Random random = new Random(); currentQ = quesList.get(random.nextInt(quesList.size()));

完整代码在这里。

public class QuestionActivity extends Activity {
    List<Question> quesList;

    int score = 0;
    int qid = 0;    

    Question currentQ;
    TextView txtQuestion, times, scored;
    Button button1, button2, button3;    

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

        QuizHelper db = new QuizHelper(this);  // my question bank class
        quesList = db.getAllQuestions();  // this will fetch all quetonall questions
        Random random = new Random(); currentQ = quesList.get(random.nextInt(quesList.size()));
      //  currentQ = quesList.get(qid); // the current question

        txtQuestion = (TextView) findViewById(R.id.txtQuestion);
        // the textview in which the question will be displayed

        // the three buttons,
        // the idea is to set the text of three buttons with the options from question bank
        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);
        button3 = (Button) findViewById(R.id.button3);

        // the textview in which score will be displayed
        scored = (TextView) findViewById(R.id.score);

        // the timer
        times = (TextView) findViewById(R.id.timers);    

        // method which will set the things up for our game
        setQuestionView();
        times.setText("00:02:00");

        // A timer of 60 seconds to play for, with an interval of 1 second (1000 milliseconds)
        CounterClass timer = new CounterClass(80000, 1000);
        timer.start();

        // button click listeners
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                // passing the button text to other method
                // to check whether the anser is correct or not
                // same for all three buttons
                getAnswer(button1.getText().toString());
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getAnswer(button2.getText().toString());
            }
        });

        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getAnswer(button3.getText().toString());
            }
        });
    }

    public void getAnswer(String AnswerString) {
        if (currentQ.getANSWER().equals(AnswerString)) {

            // if conditions matches increase the int (score) by 1
            // and set the text of the score view
            score++;
            scored.setText("Score : " + score);
        } else {

            // if unlucky start activity and finish the game

            Intent intent = new Intent(QuestionActivity.this,
                    ResultActivity.class);

            // passing the int value
            Bundle b = new Bundle();
            b.putInt("score", score); // Your score
            intent.putExtras(b); // Put your score to your next
            startActivity(intent);
            finish();
        }
        if (qid < 25) {

            // if questions are not over then do this
            currentQ = quesList.get(qid);
            setQuestionView();
        } else {

            // if over do this
            Intent intent = new Intent(QuestionActivity.this,
                    ResultActivity.class);
            Bundle b = new Bundle();
            b.putInt("score", score); // Your score
            intent.putExtras(b); // Put your score to your next
            startActivity(intent);
            finish();
        }    
    }    

    @TargetApi(Build.VERSION_CODES.GINGERBREAD)
    @SuppressLint("NewApi")
    public class CounterClass extends CountDownTimer {

        public CounterClass(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
            // TODO Auto-generated constructor stub
        }

        @Override
        public void onFinish() {
            times.setText("Time is up");
        }

        @Override
        public void onTick(long millisUntilFinished) {
            // TODO Auto-generated method stub

            long millis = millisUntilFinished;
            String hms = String.format(
                    "%02d:%02d:%02d",
                    TimeUnit.MILLISECONDS.toHours(millis),
                    TimeUnit.MILLISECONDS.toMinutes(millis)
                            - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS
                            .toHours(millis)),
                    TimeUnit.MILLISECONDS.toSeconds(millis)
                            - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS
                            .toMinutes(millis)));
            System.out.println(hms);
            times.setText(hms);
        }   
    }

    private void setQuestionView() {

        // the method which will put all things together
        txtQuestion.setText(currentQ.getQUESTION());
        button1.setText(currentQ.getOPTA());
        button2.setText(currentQ.getOPTB());
        button3.setText(currentQ.getOPTC());

        qid++;
    }       
} 

Answer 1

这是由于qid仅增加1。并且使用

currentQ = quesList.get(qid);

在你的 getAnswer() 上。使您的 Random 全局化，然后尝试将 currentQ 更改为

currentQ = quesList.get(random.nextInt(quesList.size()));

和here是如何避免重复随机的。

[编辑]

好的，为了更简单，这样做可以避免重复。进行全局 int 仓位

position = random.nextInt(quesList.size())
currentQ = quesList.get(position);

然后在 setQuestion 的末尾

quesList.remove(position);

就是这样，问题永远不会重复。希望有帮助。