Insert more items into an Android Listview

Question

I am a beginner in Java/Android programming, and would like a help with adding items to a Listview.

The app receives the first 5 records from a Json (Url), and adds in Listview, so far, all right.

The app then displays a button, which when clicking, queries the next 5 records.

Here is my doubt: the app replaces the first 5 records for the next 5, and I need this new content query to be added to the end of Listview and not replace what was already.

Go below, snippets of the code

Main Activity

// Populando Campeoes ListView
private void popularCampeoes() {
    ArrayList<Campeoes> newCampeoes = Campeoes.fromJson(JsonCampeoes);
    CampeoesAdapter adapterCampeoes = new CampeoesAdapter(this, newCampeoes);

    ListView listClubeCampeoes = (ListView) findViewById(R.id.listClubeCampeoes);
    listClubeCampeoes.setAdapter(adapterCampeoes);
}

With Json downloaded, the app invokes the popularCampeoes method();

Campeoesadapter

class CampeoesAdapter extends ArrayAdapter<Campeoes> {

    CampeoesAdapter(Context context, ArrayList<Campeoes> campeoes) {
        super(context, 0, campeoes);
    }

    private Context context;

    @NonNull
    @Override
    public View getView(int position, View convertView, @NonNull ViewGroup parent) {

        final Campeoes campeoes = getItem(position);

        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.campeoes_linha, parent, false);
        }

        TextView tvTitulo = (TextView) convertView.findViewById(R.id.clubeCampTitulo);
        TextView tvConteudo = (TextView) convertView.findViewById(R.id.clubeCampConteudo);

        assert campeoes != null;

        tvTitulo.setText(campeoes.CampTitulo);
        tvConteudo.setText(campeoes.CampConteudo);

        return convertView;
    }

}

I thank you immediately, any help you have.

Answer 1

Each time you receive new records you should add them to Arraylist and not create a new one. The same applies to Adapter.

Declare the variables listCampeoes and adapterCampeoes as attributes of Activity:

private ArrayList<Campeoes> listCampeoes;
private CampeoesAdapter adapterCampeoes;

In the method onCreate() create the Arraylist and the Adapt:

@Override
protected void onCreate(Bundle savedInstanceState) {

    ...
    ...
    ArrayList<Campeoes> listCampeoes = new ArrayList<>();
    CampeoesAdapter adapterCampeoes = new CampeoesAdapter(this, listCampeoes);

    ListView listClubeCampeoes = (ListView) findViewById(R.id.listClubeCampeoes);
    listClubeCampeoes.setAdapter(adapterCampeoes);

    ...
}

In the method popularCampeoes() add the new records to Arraylist and notify the Adapter:

// Populando Campeoes ListView
private void popularCampeoes() {
    ArrayList<Campeoes> newCampeoes = Campeoes.fromJson(JsonCampeoes);
    listCampeoes.addAll(newCampeoes);
    adapterCampeoes.notifyDataSetChanged();
}