Android测验游戏 - 每个qstion的倒数计时器

Question

我使用以下教程为Android创建了一个Quiz应用程序:http://automateddeveloper.blogspot.co.uk/2011/06/getting-started-complete-android-app.html

对于每个问题,用户只有20秒的时间来回答它.如果他/她在20秒内未能回答,AlertDialog则会弹出一个,游戏将终止.

为此,我在以下OnCreate方法中添加了一个计数器QuestionActivity class:

final TextView myCounter = (TextView) findViewById(R.id.countdown);
    new CountDownTimer(20000, 1000) {

        @Override
        public void onFinish() {
            timeUp();
        }

        @Override
        public void onTick(long millisUntilFinished) {
            myCounter.setText("Time left: "
                    + String.valueOf(millisUntilFinished / 1000));
        }

    }.start();


public void timeUp() {

    AlertDialog.Builder builder = new AlertDialog.Builder(
            QuestionActivity.this);
    builder.setTitle("Times up!")
            .setMessage("Game over")
            .setCancelable(false)
            .setNeutralButton(android.R.string.ok,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            QuestionActivity.this.finish();
                        }
                    });
    AlertDialog alert = builder.create();
    alert.show();
}

计数器正常显示和功能在屏幕上.在回答问题后,活动转到下一个问题,计数器再次重置为20秒.

问题

测验有15个问题,在回答3或4个问题后,应用程序崩溃,我收到以下错误:

07-18 00:49:05.530: E/AndroidRuntime(4867): android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@41533a80 is not valid; is your activity running?

我相信这与此有关AlertDialog.我已经在Stackoverflow上查找了这个错误代码,而流行的解决方案是ActivityName.this在构建时将其作为上下文传递AlertDialog.

不幸的是,这并没有解决问题.

我相信计数器为整个活动设置了20秒的时间限制.我的要求是每个问题20秒.

但是,当用户按下" Next按钮"并且活动移至下一个问题时,计数器将重置为20秒.

当用户按下Next按钮时,我应该重置计数器吗？这是按钮的OnClickListener代码Next

if (currentGame.isGameOver()) {
        Intent i = new Intent(this, EndgameActivity.class);
        startActivity(i);
        finish();
    } else {
        Intent i = new Intent(this, QuestionActivity.class);
        startActivity(i);
                    SHOULD I ADD SOMETHING HERE?
        finish();

任何人都可以帮我编码解决我的问题的方法吗？

这是所有的代码 QuestionActivity.class

public class QuestionActivity extends SherlockActivity implements
    OnClickListener {

private Question currentQ;
private GamePlay currentGame;
private Context context;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.question);

    getSupportActionBar().hide();
    /**
     * Configure current game and get question
     */
    currentGame = ((ChuckApplication) getApplication()).getCurrentGame();
    currentQ = currentGame.getNextQuestion();

    Button nextBtn = (Button) findViewById(R.id.nextBtn);
    nextBtn.setOnClickListener(this);

    Button quitBtn = (Button) findViewById(R.id.quitBtn);
    quitBtn.setOnClickListener(new OnClickListener() {
        public void onClick(View arg0) {
            finish();
        }
    });

    //Update the question and answer options..
    setQuestions();

    final TextView myCounter = (TextView) findViewById(R.id.countdown);
    new CountDownTimer(20000, 1000) {

        @Override
        public void onFinish() {
            // myCounter.setText("Time up!");
            timeUp(context);
        }

        @Override
        public void onTick(long millisUntilFinished) {
            myCounter.setText("Time left: "
                    + String.valueOf(millisUntilFinished / 1000));
        }
    }.start();
}

public void timeUp(Context context) {

    AlertDialog.Builder builder = new AlertDialog.Builder(
            QuestionActivity.this);
    builder.setTitle("Times up!")
            .setMessage("Game over")
            .setCancelable(false)
            .setNeutralButton(android.R.string.ok,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            QuestionActivity.this.finish();
                        }
                    });
    AlertDialog alert = builder.create();
    alert.show();
}

/**
 * Method to set the text for the question and answers from the current
 * games current question
 */
private void setQuestions() {
    // set the question text from current question
    String question = Utility.capitalise(currentQ.getQuestion()) + "?";
    TextView qText = (TextView) findViewById(R.id.question);
    qText.setText(question);

    // set the available options
    List<String> answers = currentQ.getQuestionOptions();
    TextView option1 = (TextView) findViewById(R.id.answer1);
    option1.setText(Utility.capitalise(answers.get(0)));

    TextView option2 = (TextView) findViewById(R.id.answer2);
    option2.setText(Utility.capitalise(answers.get(1)));

    TextView option3 = (TextView) findViewById(R.id.answer3);
    option3.setText(Utility.capitalise(answers.get(2)));

    TextView option4 = (TextView) findViewById(R.id.answer4);
    option4.setText(Utility.capitalise(answers.get(3)));
}

public void onClick(View arg0) {
    //validate a checkbox has been selected
    if (!checkAnswer())
        return;

    //check if end of game
    if (currentGame.isGameOver()) {
        Intent i = new Intent(this, EndgameActivity.class);
        startActivity(i);
        finish();
    } else {
        Intent i = new Intent(this, QuestionActivity.class);
        startActivity(i);
        finish();
    }
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    switch (keyCode) {
    case KeyEvent.KEYCODE_BACK:
        return true;
    }

    return super.onKeyDown(keyCode, event);
}

/**
 * Check if a checkbox has been selected, and if it has then check if its
 * correct and update gamescore
 */
private boolean checkAnswer() {
    String answer = getSelectedAnswer();
    if (answer == null) {
        // Log.d("Questions", "No Checkbox selection made - returning");
        return false;
    } else {
        // Log.d("Questions",
        // "Valid Checkbox selection made - check if correct");
        if (currentQ.getAnswer().equalsIgnoreCase(answer)) {
            // Log.d("Questions", "Correct Answer!");
            currentGame.incrementRightAnswers();
        } else {
            // Log.d("Questions", "Incorrect Answer!");
            currentGame.incrementWrongAnswers();
        }
        return true;
    }
}

private String getSelectedAnswer() {
    RadioButton c1 = (RadioButton) findViewById(R.id.answer1);
    RadioButton c2 = (RadioButton) findViewById(R.id.answer2);
    RadioButton c3 = (RadioButton) findViewById(R.id.answer3);
    RadioButton c4 = (RadioButton) findViewById(R.id.answer4);
    if (c1.isChecked()) {
        return c1.getText().toString();
    }
    if (c2.isChecked()) {
        return c2.getText().toString();
    }
    if (c3.isChecked()) {
        return c3.getText().toString();
    }
    if (c4.isChecked()) {
        return c4.getText().toString();
    }

    return null;
}

Answer 1

我认为当你试图进行对话时某个时刻活动不再存在(可能CountDownTimer是在接近结束时？!？).

无论如何,我认为为每个问题完成并开始相同的活动并不是一个好主意,而是可以使用当前活动并简单地重新启动计时器.例如:

public class QuestionActivity extends SherlockActivity implements
    OnClickListener {

   private CountDownTimer mCountDown;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      // ...
      mCountDown = new CountDownTimer(20000, 1000) {

        @Override
        public void onFinish() {
            // myCounter.setText("Time up!");
            timeUp(context);
        }

        @Override
        public void onTick(long millisUntilFinished) {
            myCounter.setText("Time left: "
                    + String.valueOf(millisUntilFinished / 1000));
        }
      }.start();
      // ... 

并在onClick回调中执行相同操作以设置新问题,停止旧计时器并重新启动新计时器:

//check if end of game
if (currentGame.isGameOver()) {
    Intent i = new Intent(this, EndgameActivity.class);
    startActivity(i);
    finish();
} else {
    if (mCountDown != null) { 
       mCountDown.cancel();
    }  
    currentQ = currentGame.getNextQuestion();
    setQuestions();
    mCountDown = new CountDownTimer(20000, 1000) {

        @Override
        public void onFinish() {
            // myCounter.setText("Time up!");
            timeUp(context);
        }

        @Override
        public void onTick(long millisUntilFinished) {
            myCounter.setText("Time left: "
                    + String.valueOf(millisUntilFinished / 1000));
        }
    }.start();  
}

此外,在回调中Dialog的Button我会先关闭Dialog完成之前Activity:

((AlertDialog) dialog).dismiss();
QuestionActivity.this.finish();