在真实设备上运行时的 Android IndexOutOfBoundsException

Question

I am developing quiz application where user can solve quiz in particular time but when I am running application on emulator it runs without error but at the time of running application on real device it throws following error.

Error:-

    java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2683)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2744)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1493)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6195)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:874)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:764)
    Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at java.util.ArrayList.get(ArrayList.java:411)
    at com.gaurav.javascripttutorial.subactivities.QuizMainActivity.onCreate(QuizMainActivity.java:52)

Code:-

public class QuizMainActivity extends AppCompatActivity {

    private ProgressBar countDownTimer;
    private TextView timer;
    public int counter;

    List<Question> quesList;
    int score=0;
    int qid=0;
    Question currentQ;
    TextView txtQuestion;
    RadioButton rda, rdb, rdc;
    Button butNext;

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

        /**
         * Quiz coding
         */

        DbHelper db=new DbHelper(this);
        quesList=db.getAllQuestions();
        currentQ=quesList.get(qid);
        txtQuestion=(TextView)findViewById(R.id.textView1);
        rda=(RadioButton)findViewById(R.id.radio0);
        rdb=(RadioButton)findViewById(R.id.radio1);
        rdc=(RadioButton)findViewById(R.id.radio2);
        butNext=(Button)findViewById(R.id.nextButton);
        setQuestionView();
        butNext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                RadioGroup grp=(RadioGroup)findViewById(R.id.radioGroup1);
                RadioButton answer=(RadioButton)findViewById(grp.getCheckedRadioButtonId());
                Log.d("yourans", currentQ.getANSWER()+" "+answer.getText());
                if(currentQ.getANSWER().equals(answer.getText()))
                {
                    score++;
                    Log.d("score", "Your score"+score);
                }
                if(qid<22){
                    currentQ=quesList.get(qid);
                    setQuestionView();
                }else{
                    Intent intent = new Intent(QuizMainActivity.this, QuizResultActivity.class);
                    Bundle b = new Bundle();
                    b.putInt("score", score); //Your score
                    intent.putExtras(b); //Put your score to your next Intent
                    startActivity(intent);
                    finish();
                }
            }
        });

        /**
         * Timer Coding
         */
        countDownTimer = (ProgressBar) findViewById(R.id.progressBar);
        timer = (TextView) findViewById(R.id.timer);

        new CountDownTimer(1200000,1000){

            @Override
            public void onTick(long millisUntilFinished) {
                int progress = (int) (millisUntilFinished/120000)+1;
                countDownTimer.setProgress(countDownTimer.getMax()-progress);
                if (counter == 1080){
                    Toast.makeText(QuizMainActivity.this, "Only 2 minutes remaining, Please review the answers.", Toast.LENGTH_SHORT).show();
                }
               counter++;
                Log.d("Counter number", ""+counter);
            }

            @Override
            public void onFinish() {
                Toast.makeText(QuizMainActivity.this, "Sorry! Time is over, Try again", Toast.LENGTH_LONG).show();
                finish();
            }
        }.start();
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
        finish();
    }

    private void setQuestionView()
    {
        txtQuestion.setText(currentQ.getQUESTION());
        rda.setText(currentQ.getOPTA());
        rdb.setText(currentQ.getOPTB());
        rdc.setText(currentQ.getOPTC());
        qid++;
    }
}

When program runs and error throws the cursor denote to the following line of a code:-

currentQ=quesList.get(qid);

Answer 1

Please check the gelAllQuestions() function. First of all if the function not returning empty list, you should null check. After that, you can check is the list empty with isEmpty() function.

Please be sure there are available data in database.

Answer 2

After create a List, you must implement it with it's constructor. So add this line before use your List:

    quesList = new ArrayList<>();