ONCREATE SLIDE 26
FirebaseApp.initializeApp(this);

        //Create database reference
        databaseArtists = FirebaseDatabase.getInstance().getReference("artists");
        //get values from XML
        editTextName = (EditText) findViewById(R.id.editTextName);
        buttonAdd = (Button) findViewById(R.id.buttonAddArtist);

        //listViewArtists = (ListView) findViewById(R.id.ListViewArtist);
        //artistList = new ArrayList<>();

        //attach clicklistener to the button
        buttonAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                addArtist();
            } });


Add artist slide 27
 private void addArtist() {
        //get artistname and convert to string from editextname
        String name = editTextName.getText().toString().trim();

        //check if the name is not empty
        if (!TextUtils.isEmpty(name)) {
            //if exist push data to firebase database
            //store inside id in database
            //every time data stored the id will be unique
            String id = databaseArtists.push().getKey();
            //store
            Artist artist = new Artist(id, name);
            //store artist inside unique id
            databaseArtists.child(id).setValue(artist);
            Toast.makeText(this, "Artist added", Toast.LENGTH_LONG).show();

        } else {
            //if the name is empty
            //if the value is not given displaying a toast
            Toast.makeText(this, "Please enter a name", Toast.LENGTH_LONG).show();
        }
    }


Artist list slide 38
public class ArtistList extends ArrayAdapter<Artist> {
    private Activity context;
    List<Artist> artists;

    //Create constructor
    public ArtistList(Activity context, List<Artist> artists) {
        super(context, R.layout.list_layout, artists);
        this.context = context;
        this.artists = artists;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = context.getLayoutInflater();
        View listViewItem = inflater.inflate(R.layout.list_layout, null, true);

        TextView textViewName = (TextView) listViewItem.findViewById(R.id.textViewName);

        Artist artist = artists.get(position);
        textViewName.setText(artist.getArtistName());

        return listViewItem;
    }
}


onstart method
@Override
    protected void onStart() {
        super.onStart();
        //attaching value event listener
        databaseArtists.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                //clearing the previous artist list
                artistList.clear();

                //iterating through all the nodes
                for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                    //getting artist
                    Artist artist = postSnapshot.getValue(Artist.class);
                    //adding artist to the list
                    artistList.add(artist);
                }

                //creating adapter
                ArtistList artistAdapter = new ArtistList(MainActivity.this, artistList);
                //attaching adapter to the listview
                listViewArtists.setAdapter(artistAdapter);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }