Display Firebase database content in a FirebaseLis

Question

I am currently experimenting with Firebase by creating a kind of small chat app. I am able to send data to the database reference, however I would expect it to be displayed thanks to the following code. However that is not the case, I was wondering if there was something wrong with the way I am using the adapter for my list.

      protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if(FirebaseAuth.getInstance().getCurrentUser() == null) {
            // Start sign in/sign up activity
            startActivityForResult(
                    AuthUI.getInstance().createSignInIntentBuilder().build(),
                    SIGN_IN_REQUEST_CODE
            );
        } else {
            // User is already signed in. Therefore, display
            // a welcome Toast
            Toast.makeText(this,
                    "Welcome " + FirebaseAuth.getInstance()
                            .getCurrentUser()
                            .getDisplayName(),
                    Toast.LENGTH_LONG)
                    .show();

            displayChatMessages();
        }

        FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                EditText input = (EditText)findViewById(R.id.input);

                // Read the input field and push a new instance
                // of ChatMessage to the Firebase database
                FirebaseDatabase.getInstance()
                        .getReference()
                        .push()
                        .setValue(new ChatMessage(input.getText().toString(),
                                FirebaseAuth.getInstance()
                                        .getCurrentUser()
                                        .getDisplayName())
                        );

                // Clear the input
                input.setText("");
            }
        });

    }

    private void displayChatMessages() {
        ListView listOfMessages = (ListView)findViewById(R.id.list_of_messages);

        Query query = FirebaseDatabase.getInstance().getReference();

        FirebaseListOptions<ChatMessage> options = new FirebaseListOptions.Builder<ChatMessage>()
                .setQuery(query, ChatMessage.class)
                .setLayout(R.layout.message)
                .build();

        adapter = new FirebaseListAdapter<ChatMessage>( options ) {
            @Override
            protected void populateView(View v, ChatMessage model, int position) {
                // Get references to the views of message.xml
                TextView messageText = (TextView)v.findViewById(R.id.message_text);
                TextView messageUser = (TextView)v.findViewById(R.id.message_user);
                TextView messageTime = (TextView)v.findViewById(R.id.message_time);

                // Set their text
                messageText.setText(model.getMessageText());
                messageUser.setText(model.getMessageUser());
                messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)",
                        model.getMessageTime()));
            }
        };

        listOfMessages.setAdapter(adapter);

    }

 @Override
    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == SIGN_IN_REQUEST_CODE) {
            if(resultCode == RESULT_OK) {
                Toast.makeText(this,
                        "Successfully signed in. Welcome!",
                        Toast.LENGTH_LONG)
                        .show();
                displayChatMessages();
            } else {
                Toast.makeText(this,
                        "We couldn't sign you in. Please try again later.",
                        Toast.LENGTH_LONG)
                        .show();

                // Close the app
                finish();
            }
        }

    }

}

Here is the UI of the main activity

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="citroentrex.citron.MainActivity">

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:clickable="true"
        android:tint="@android:color/white"
        app:fabSize="mini"
        />

    <android.support.design.widget.TextInputLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_toLeftOf="@id/fab"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="Input"
            android:id="@+id/input"
            />
    </android.support.design.widget.TextInputLayout>

    <ListView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_alignParentTop="true"
      android:layout_alignParentLeft="true"
      android:dividerHeight="16dp"
      android:divider="@android:color/transparent"
      android:layout_above="@id/fab"
      android:id="@+id/list_of_messages"
      android:layout_marginBottom="16dp"
      />

</RelativeLayout>

and of the message

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:id="@+id/message_user"
        android:textStyle="normal|bold" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/message_user"
        android:layout_alignParentRight="true"
        android:id="@+id/message_time" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/message_user"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="5dp"
        android:id="@+id/message_text"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:textSize="18sp" />
</RelativeLayout>

displayChatMessages is the bit wher I would expect the adapter to display the data content in my list. (Pushing data to the database works for sure) This is the model of my database. (there are no child)

Answer 1

The adapter had to be initialised as follow:

@Override
protected void onStart() {
    super.onStart();
    adapter.startListening();
}


@Override
protected void onStop() {
    super.onStop();
    adapter.stopListening();
}