How do I retrieve data from firebase database Storage and displaying it into custom listview?

Question

I find difficult to display my communities node in ListView. This is my tree in Firebase : My Firebase tree

I would like to display in ListView in Android List of three items containing the three community (community1, 2 , 3) with their details MessageSentCount, MessageReceivedCount.

I'm newbie in Android also in Firebase, I followed many tutorials and while trying the application crashes My class :

    DatabaseReference dref;
    ListView listView;
    ArrayList<String> list = new ArrayList<>();
    ArrayAdapter<String> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_analyze);

    listView =(ListView)findViewById(R.id.listview);
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line,list);
    listView.setAdapter(adapter);

    dref = FirebaseDatabase.getInstance().getReference("clusters");
    dref.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            String value = dataSnapshot.getValue(String.class);
            list.add(value);
            adapter.notifyDataSetChanged();
        }

My layout.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="0dip"
        android:layout_weight="1"/>
    <Button
        android:id="@+id/button_discover"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:text="@string/button_discover"
        android:onClick="discoverYourself"/>
</LinearLayout>

I have checked many tutorials but haven't find the solution. Kindly help me out.

Thank you :)

Answer 1

• hi , please try to add Log message when child added

  public void onChildAdded(DataSnapshot dataSnapshot, String s) { String value = dataSnapshot.getValue(String.class); Log.e("value",value) list.add(value); adapter.notifyDataSetChanged(); }

  to be sure that there is some child and the problem is on your listview

• then try to change : adapter.notifyDataSetChanged(); by adapter.notifyItemInserted(list.size()-1);

• also try to change this on your xml : android:layout_height="0dip" by : android:layout_height="wrap_content"

to fix converting exception:

dref = FirebaseDatabase.getInstance().getReference("clusters/Community");
dref.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
String name = dataSnapshot.child("name").getValue(String.class);
int messagesSentCount = dataSnapshot.child("messagesSentCount").getValue(Integer.class);
list.add(name);
adapter.notifyItemInserted(list.size()-1);
}