Firebase App / Not loading questions - firebase-realtime-database

Question

Hey i made a firebase quiz app but the questions stored in the database don't load in the app. can someone tell me what is wrong ?
This is the code to load questions :
public class Start extends AppCompatActivity {
Button btnLigue1, btnChampionsligue;
FirebaseDatabase database;
DatabaseReference questions;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
database = FirebaseDatabase.getInstance();
questions = database.getReference("Questions");
loadQuestion();
btnChampionsligue = (Button)findViewById(R.id.btnChampionsligue);
btnLigue1 = (Button)findViewById(R.id.btnLigue1);
btnChampionsligue.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent1 = new Intent(Start.this,Playing2.class);
startActivity(intent1);
finish();
}
});
btnLigue1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(Start.this,Playing.class);
startActivity(intent);
finish();
}
});
}
private void loadQuestion() {
// Fist, clear List if have old question
if (Common.questionList.size() > 0)
Common.questionList.clear();
questions.orderByChild("Questions").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot postSnapchot : dataSnapshot.getChildren())
{
Question ques = postSnapchot.getValue(Question.class);
Common.questionList.add(ques);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
// Random list
Collections.shuffle(Common.questionList);
}
}
And this is the code when i am playing :
public class Playing extends AppCompatActivity implements View.OnClickListener{
private DatabaseReference mDatabase;
final static long INTERVAL = 1000;
final static long TIMEOUT = 7000;
int progressValue = 0;
CountDownTimer mCountDown;
int index=0,score=0,thisQuestion=0,totalQuestion,correctAnswer;
ProgressBar progressBar;
ImageView question_image;
Button btnA,btnB,btnC,btnD;
TextView txtScore,txtQuestionNum,question_text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_playing);
mDatabase = FirebaseDatabase.getInstance().getReference("Questions");
//Views
txtScore = (TextView)findViewById(R.id.txtScore);
txtQuestionNum = (TextView)findViewById(R.id.txtTotalQuestion);
question_text = (TextView)findViewById(R.id.question_text);
question_image = (ImageView)findViewById(R.id.question_image);
progressBar = (ProgressBar)findViewById(R.id.progressBar);
btnA = (Button)findViewById(R.id.btnAnswerA);
btnB = (Button)findViewById(R.id.btnAnswerB);
btnC = (Button)findViewById(R.id.btnAnswerC);
btnD = (Button)findViewById(R.id.btnAnswerD);
btnA.setOnClickListener(this);
btnB.setOnClickListener(this);
btnC.setOnClickListener(this);
btnD.setOnClickListener(this);
}
#Override
public void onClick(View view) {
mCountDown.cancel();
if (index < totalQuestion) // Il reste des questions dans la liste
{
Button clickedButton =(Button)view;
if(clickedButton.getText().equals(Common.questionList.get(index).getCorrectAnswer()))
{
score+=10;
correctAnswer++;
showQuestion(++index); // Question suivante
}
else if (clickedButton.getText()!=(Common.questionList.get(index).getCorrectAnswer()))
{
showQuestion(++index);
}
else
{
// Si mauvaise question TODOO proposer de regarder une pub pour passer à la question suivante
Intent intent = new Intent(this,Done.class);
Bundle dataSend = new Bundle();
dataSend.putInt("SCORE", score);
dataSend.putInt("TOTAL", totalQuestion);
dataSend.putInt("CORRECT", correctAnswer);
intent.putExtras(dataSend);
//startActivity(intent);
finish();
}
txtScore.setText(String.format("%d",score));
}
}
private void showQuestion(int index) {
if (index < totalQuestion)
{
thisQuestion++;
txtQuestionNum.setText(String.format("%d / %d",thisQuestion,totalQuestion));
progressBar.setProgress(0);
progressValue=0;
if(Common.questionList.get(index).getIsImageQuestion().equals("true"))
{
// Si il y a une image
Picasso.with(getBaseContext())
.load(Common.questionList.get(index).getQuestion())
.into(question_image);
question_image.setVisibility(View.VISIBLE);
question_text.setVisibility(View.INVISIBLE);
}
else
{
question_text.setText(Common.questionList.get(index).getQuestion());
// Si c'est une question texte : masquer l'image
question_image.setVisibility(View.INVISIBLE);
question_text.setVisibility(View.VISIBLE);
}
btnA.setText(Common.questionList.get(index).getAnswerA());
btnB.setText(Common.questionList.get(index).getAnswerB());
btnC.setText(Common.questionList.get(index).getAnswerC());
btnD.setText(Common.questionList.get(index).getAnswerD());
mCountDown.start(); // Start timer
}
else
{
// Si c'est la dernière question
Intent intent = new Intent(this,Done.class);
Bundle dataSend = new Bundle();
dataSend.putInt("SCORE", score);
dataSend.putInt("TOTAL", totalQuestion);
dataSend.putInt("CORRECT", correctAnswer);
intent.putExtras(dataSend);
// startActivity(intent);
// finish();
}
}
#Override
protected void onResume() {
super.onResume();
totalQuestion = Common.questionList.size();
mCountDown = new CountDownTimer(TIMEOUT,INTERVAL) {
#Override
public void onTick(long minisec) {
progressBar.setProgress(progressValue);
progressValue++;
}
#Override
public void onFinish() {
mCountDown.cancel();
showQuestion(++index);
}
};
showQuestion(index);
}
}