实现定时器的最佳方式是什么？

Question

我在写一个需要显示计时器的Android测验应用程序。实现定时器的最佳方式是什么？ 我是新来的android和这是我的第一个应用程序。我尝试使用处理程序。这工作，但似乎并不高效。

public class PertanyaanActivity extends Activity 
{ 

    private Handler progressBarHandler = new Handler(); 
    ProgressBar progressBar; 
    TextView progressText; 
    PertanyaanData mQuestionData; 
    JawabanData mAnswerData; 

    private int mCategoryId; 
    private Map<Integer, Pertanyaan> mQuestions; 
    private Map<Integer, Jawaban> mAnswers; 

    private List<Integer> mQuestionIndexList; 
    private int mNextQuestionIndex = 0; 

    private int mTotalQuestions = 0; 
    private int mQuestionsAnswered = 0; 
    private int mCorrectAnswers = 0; 

    private Pertanyaan mCurrentQuestion; 

    private List<Button> answerButtons; 

    private LinearLayout.LayoutParams mAnswerButtonLayout; 

    // private TextView mViewHeader; 
    private ScrollView mQuestionScrollView; 
    private TextView mQuestionText; 
    private LinearLayout mAnswersFrame; 
    private TextView mQuestionDescriptionText; 
    // private Button mNextQuestionButton; 
    // private Button mCompleteButton; 
    private int max_salah = 0; 
    private int progressBarStatus = 0; 
    private long fileSize = 0; 

    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.question); 
     mCategoryId = getIntent().getIntExtra("categoryId", 0); 

     Log.i(Constants.APP_LOG_NAME, "Getting question for category ID " + mCategoryId); 

     mAnswerButtonLayout = new LinearLayout.LayoutParams(
       LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT); 
     mAnswerButtonLayout.setMargins(30, 20, 30, 0); 

     // mViewHeader = (TextView)findViewById(R.id.viewHeader); 
     mQuestionScrollView = (ScrollView)findViewById(R.id.questionScrollView); 
     mQuestionText = (TextView)findViewById(R.id.questionText); 
     mAnswersFrame = (LinearLayout)findViewById(R.id.answersFrame); 

     progressText=(TextView)findViewById(R.id.progressText); 
     progressBar= (ProgressBar) findViewById(R.id.ProgressBar01); 
     // progressBar.setProgress(0); 
     //progressBar.setMax(100); 
     waktu(); 
     //mQuestionDescriptionText = (TextView)findViewById(R.id.questionDescriptionText); 
    // mNextQuestionButton = (Button)findViewById(R.id.nextQuestionButton); 
     //mCompleteButton = (Button)findViewById(R.id.completeButton); 

     mQuestionData = new PertanyaanData(this); 
     mAnswerData = new JawabanData(this); 

     mQuestions = mQuestionData.getQuestionsByCategoryId(mCategoryId); 

     mQuestionIndexList = new ArrayList<Integer>(); 

     for (int questionId : mQuestions.keySet()) 
     { 
      mQuestionIndexList.add(questionId); 
     } 

     Collections.shuffle(mQuestionIndexList); 

     if (mQuestionIndexList.size() > (Constants.MAX_QUESTIONS_PER_ROUND)) 
     { 
      mQuestionIndexList = mQuestionIndexList.subList(0, Constants.MAX_QUESTIONS_PER_ROUND); 
     } 

     mTotalQuestions = mQuestionIndexList.size(); 

     Log.i(Constants.APP_LOG_NAME, "Total questions: " + mTotalQuestions); 

     if (mTotalQuestions > 0) 
     { 
      displayNextQuestion(); 
     } 
     else 
     { 
      Log.e(Constants.APP_LOG_NAME, "No questions found for category ID " + mCategoryId); 
     } 

     setVolumeControlStream(AudioManager.STREAM_MUSIC); 
    } 

    @Override 
    public void onDestroy() 
    { 
     super.onDestroy(); 

     if (mQuestionData != null) 
     { 
      mQuestionData.close(); 
     } 

     if (mAnswerData != null) 
     { 
      mAnswerData.close(); 
     } 
    } 

    /** 
    * Displays the next available question in the current trivia round. 
    */ 
    public void displayNextQuestion() 
    { 
     // Reset ScrollView position. 
     mQuestionScrollView.scrollTo(0, 0); 

     waktu(); 
     mCurrentQuestion = getNextQuestion(); 

     String headerText = getString(R.string.question) 
       + " " + mNextQuestionIndex 
       + " " + getString(R.string.of) 
       + " " + mTotalQuestions; 

     //mViewHeader.setText(headerText); 

     //nyalakanWaktu(); 
     //waktu(); 
     displayQuestion(mCurrentQuestion); 

     // mQuestionDescriptionText.setVisibility(View.GONE); 
     // mNextQuestionButton.setVisibility(View.GONE); 
    } 

    /** 
    * Gets the next available question in the current trivia round. 
    * 
    * @return Question - The instance of the next available question. 
    */ 
    private Pertanyaan getNextQuestion() 
    { 
     int nextQuestionId = mQuestionIndexList.get(mNextQuestionIndex); 

     Log.i(Constants.APP_LOG_NAME, "Got next question ID " + nextQuestionId); 

     Pertanyaan question = mQuestions.get(nextQuestionId); 

     if (question == null) 
     { 
      Log.w(Constants.APP_LOG_NAME, "Next question is null."); 
     } 

     mNextQuestionIndex++; 

     return question; 
    } 

    /** 
    * Displays a question on the screen. 
    * 
    * @param Question question - The question instance to display. 
    */ 
    private void displayQuestion(Pertanyaan question) 
    { 
     if (question != null) 
     { 
      mAnswers = mAnswerData.getAnswersByQuestionId(question.getPertanyaanId()); 

      List<Integer> answerIndexList = new ArrayList<Integer>(); 

      for (int answerId : mAnswers.keySet()) 
      { 
       answerIndexList.add(answerId); 
      } 

      Collections.shuffle(answerIndexList); 

      mAnswersFrame.removeAllViews(); 

      mQuestionText.setText(question.getText()); 

      if (mAnswers != null) 
      { 
       answerButtons = new ArrayList<Button>(); 

       Jawaban answer = null; 

       for (int answerId : answerIndexList) 
       { 
        Log.i(Constants.APP_LOG_NAME, "Adding answer ID " + answerId); 

        answer = mAnswers.get(answerId); 

        Button answerButton = new Button(this); 
        answerButton.setId(answer.getJawabanId()); 
        answerButton.setText(answer.getText()); 
        answerButton.setBackgroundResource(R.drawable.button_normal); 

        answerButton.setOnClickListener(new View.OnClickListener() 
        { 
         public void onClick(View v) 
         { 
          disableAnswerButtons(); 

          answerButtonClickHandler(v); 
         } 
        }); 

        answerButtons.add(answerButton); 

        mAnswersFrame.addView(answerButton, mAnswerButtonLayout); 
       } 
      } 
     } 
     else 
     { 
      // TODO: Need to handle this in a more user-friendly way. 
      mQuestionText.setText("Null question."); 
     } 
    } 

    /** 
    * Click handler for answer option buttons. 
    * Determines the result of the user selecting an answer. 
    * 
    * @param View v - The current view. 
    */ 
    public void answerButtonClickHandler(View v) 
    { 
     Jawaban answer = mAnswers.get(v.getId()); 

     if (answer != null) 
     { 
      mQuestionsAnswered++; 

      if (answer.isCorrect()) 
      { 
       mCorrectAnswers++; 

       v.setBackgroundResource(R.drawable.answer_button_correct); 

       Suara.playButtonClickSuccess(); 
      } 
      else 
      { 
       max_salah++; 
       v.setBackgroundResource(R.drawable.answer_button_incorrect); 

       Suara.playButtonClickFailure(); 

      } 

      // mQuestionDescriptionText.setText(mCurrentQuestion.getDescription()); 
      //mQuestionDescriptionText.setVisibility(View.VISIBLE); 

      if (mNextQuestionIndex < mQuestionIndexList.size() && max_salah < 3) 
      { 
       //mNextQuestionButton.setVisibility(View.VISIBLE); 


       //nyalakanWaktu(); 
       waktu(); 
       displayNextQuestion(); 
      } 
      else 
      { 


       Intent i = new Intent(this, SummaryActivity.class); 
       i.putExtra("categoryId", mCategoryId); 
       i.putExtra("questionsAnswered", mQuestionsAnswered); 
       i.putExtra("correctAnswers", mCorrectAnswers); 
       startActivity(i); 
       //mCompleteButton.setVisibility(View.VISIBLE); 
      } 
     } 
    } 

    /** 
    * Click handler for the next question button. 
    * Displays the next available question after current question is answered. 
    * 
    * @param View v - The current view. 
    */ 
    public void nextQuestionButtonClickHandler(View v) 
    { 
     displayNextQuestion(); 

     Suara.playButtonClick(); 
    } 

    /** 
    * Click handler for the trivia round completion button. 
    * Displays the round summary screen when clicked. 
    * 
    * @param View v - The current view. 
    */ 
    public void completeButtonClickHandler(View v) 
    { 
     Intent i = new Intent(this, SummaryActivity.class); 
     i.putExtra("categoryId", mCategoryId); 
     i.putExtra("questionsAnswered", mQuestionsAnswered); 
     i.putExtra("correctAnswers", mCorrectAnswers); 
     startActivity(i); 
    } 

    /** 
    * Disables all answer buttons. 
    * Used after an answer is selected. 
    */ 
    private void disableAnswerButtons() 
    { 
     Button answerButton = null; 

     for (int i = 0; i < answerButtons.size(); i++) 
     { 
      answerButton = answerButtons.get(i); 
      answerButton.setEnabled(false); 
     } 
    } 

    public void nyalakanWaktu(){ 
     final Handler handler = new Handler(); 
     Timer timer = new Timer(); 
     TimerTask doAsynchronousTask = new TimerTask() { 

      @Override 
      public void run() { 
       handler.post(new Runnable() { 
        public void run() { 
         try { 
          progressBar.incrementProgressBy(1); 
          int stringProgress=progressBar.getProgress(); 
          progressText.setText(stringProgress+""); 
         } catch (Exception e) { 
         } 
        } 
       }); 
      } 

     };timer.schedule(doAsynchronousTask, 0, 200); 
     //audioBackground.stop(); 

    } 

Answer 1

您可以使用CountDownTimer

 new CountDownTimer(30000, 1000) { 

    public void onTick(long millisUntilFinished) { 
     mTextField.setText("seconds remaining: " + millisUntilFinished/1000); 
    } 

    public void onFinish() { 
     mTextField.setText("done!"); 
    } 
    }.start(); 

我认为它能够更好地使用CountDownTimer当你有时间限制。在上面的例子中，30000是时间限制，间隔为1000毫秒。 30分钟后，onfinish()将被呼叫。你可以在onTick()上写下自己的时间逻辑。

更好地解释here