我的倒数计时器工作正常，但是当我在时间的运行状态下使用后退键时，我的倒数计时器没有停止。我已经尝试了以下所有方法，但是它们都无法停止倒数计时器在后台运行。搜索论坛并将其结果应用于我的项目后，我无法弄清楚代码中的错误。请任何人帮助我，我将非常感激。
public class QuizActivity extends AppCompatActivity {
private static final long COUNTDOWN_IN_MILLIS = 30000 ;
List<Questions> mQuestions;
int score = 0;
int qid = 0;
Questions currentQ;
TextView txtQuestions, textViewCountDown;
RadioButton rda, rdb, rdc;
Button btnNext;
private QuestionsViewModel questionsViewModel;
private RelativeLayout relativeLayout;
private LinearLayout linearLayout;
private ColorStateList textColorDefaultCd;
private CountDownTimer countDownTimer;
private long timeLeftInMillis;
private Handler handler;
private Runnable runnable = new Runnable() {
@Override
public void run() {
takeAction();
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_quiz);
textViewCountDown = findViewById(R.id.text_view_countdown);
relativeLayout = (RelativeLayout)findViewById(R.id.profileLoadingScreen);
linearLayout = (LinearLayout) findViewById(R.id.linearView);
textColorDefaultCd = textViewCountDown.getTextColors();
fetchQuestions();
questionsViewModel = ViewModelProviders.of(QuizActivity.this).get(QuestionsViewModel.class);
questionsViewModel.getAllQuestions().observe(this, new Observer<List<Questions>>() {
@Override
public void onChanged(@Nullable final List<Questions> words) {
// Update the cached copy of the words in the adapter.
mQuestions = words;
//Collections.shuffle(mQuestions);
Collections.addAll(mQuestions);
}
});
}
private void fetchQuestions() {
DataServiceGenerator dataServiceGenerator = new DataServiceGenerator();
Service service = DataServiceGenerator.createService(Service.class);
Call<List<QuestionsModel>> call = service.getQuestions();
call.enqueue(new Callback<List<QuestionsModel>>() {
@Override
public void onResponse(Call<List<QuestionsModel>> call, Response<List<QuestionsModel>> response) {
if (response.isSuccessful()){
if (response != null){
List<QuestionsModel> questionsModelList = response.body();
for (int i = 0; i < questionsModelList.size(); i++){
String question = questionsModelList.get(i).getQuestion();
String answer = questionsModelList.get(i).getAnswer();
String opta = questionsModelList.get(i).getOpta();
String optb = questionsModelList.get(i).getOptb();
String optc = questionsModelList.get(i).getOptc();
Questions questions = new Questions(question, answer, opta, optb, optc);
questionsViewModel.insert(questions);
}
handler = new Handler();//add this
handler.postDelayed(runnable,3000);
/* Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
takeAction();
}
}, 3000); */
}
}else{
}
}
@Override
public void onFailure(Call<List<QuestionsModel>> call, Throwable t) {
}
});
}
private void setQuestionView()
{
txtQuestions.setText(currentQ.getQuestion());
rda.setText(currentQ.getOptA());
rdb.setText(currentQ.getOptB());
rdc.setText(currentQ.getOptC());
qid++;
}
private void startCountDown() {
countDownTimer = new CountDownTimer(timeLeftInMillis, 1000) {
@Override
public void onTick(long millisUntilFinished) {
timeLeftInMillis = millisUntilFinished;
updateCountDownText();
}
@Override
public void onFinish() {
timeLeftInMillis = 0;
updateCountDownText();
Intent intent = new Intent(QuizActivity.this, ResultActivity.class);
Bundle b = new Bundle();
b.putInt("score", score); //Your score
intent.putExtras(b); //Put your score to your next Intent
startActivity(intent);
finish();
}
}.start();
}
private void updateCountDownText() {
int minutes = (int) (timeLeftInMillis / 1000) / 60;
int seconds = (int) (timeLeftInMillis / 1000) % 60;
String timeFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);
textViewCountDown.setText(timeFormatted);
if (timeLeftInMillis < 10000) {
textViewCountDown.setTextColor(Color.RED);
} else {
textViewCountDown.setTextColor(textColorDefaultCd);
}
}
private void takeAction() {
relativeLayout.setVisibility(View.GONE);
linearLayout.setVisibility(View.VISIBLE);
textViewCountDown.setVisibility(View.VISIBLE);
timeLeftInMillis = COUNTDOWN_IN_MILLIS;
startCountDown();
currentQ = mQuestions.get(qid);
txtQuestions = (TextView)findViewById(R.id.textView1);
rda=(RadioButton)findViewById(R.id.radio0);
rdb=(RadioButton)findViewById(R.id.radio1);
rdc=(RadioButton)findViewById(R.id.radio2);
btnNext=(Button)findViewById(R.id.button1);
setQuestionView();
btnNext.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
RadioGroup grp=(RadioGroup)findViewById(R.id.radioGroup1);
if (grp.getCheckedRadioButtonId() == -1){
Toast.makeText(getApplicationContext(),
"Please Select an Answer",
Toast.LENGTH_SHORT)
.show();
return;
}else{
// countDownTimer.cancel();
}
RadioButton answer=(RadioButton)findViewById(grp.getCheckedRadioButtonId());
grp.clearCheck();
//Log.d("yourans", currentQ.getANSWER()+" "+answer.getText());
if(currentQ.getAnswer().equals(answer.getText()))
{
score++;
Log.d("score", "Your score"+score);
}else{
}
if(qid<10){
currentQ=mQuestions.get(qid);
setQuestionView();
}else{
Intent intent = new Intent(QuizActivity.this, ResultActivity.class);
Bundle b = new Bundle();
b.putInt("score", score); //Your score
intent.putExtras(b); //Put your score to your next Intent
startActivity(intent);
finish();
}
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
if(handler!=null){
handler.removeCallbacks(runnable);
}
if (countDownTimer != null) {
countDownTimer.cancel();
countDownTimer = null;
}
finish();
}
@Override
protected void onPause() {
super.onPause();
if(handler!=null){
handler.removeCallbacks(runnable);
}
if (countDownTimer!=null) {
countDownTimer.cancel();
countDownTimer = null;
}
finish();
}
@Override
protected void onStop() {
super.onStop();
if(handler!=null){
handler.removeCallbacks(runnable);
}
if (countDownTimer!=null) {
countDownTimer.cancel();
countDownTimer = null;
}
finish();
}
@Override
public void onBackPressed() {
if (countDownTimer!=null) {
countDownTimer.cancel();
countDownTimer = null;
}
finish();
}
}
答案 0 :(得分：0)
尝试此代码
@Override
public void onBackPressed() {
if(handler!=null){
handler.removeCallbacks(runnable);
}
if (countDownTimer!=null) {
countDownTimer.cancel();
countDownTimer = null;
}
finish();
}