How to save spinner items in firebase

Question

I’m a beginner in android studio and I stuck in a part, I already looked here in the stack I saw some possible solutions but they didn’t work for me, I don’t know if it’s because of my code, come on, I have 2 spinners that receive data from firebase to complement a form, I am unable to save this form with the selected data in the spinner. If anyone can help me, I’d be most grateful. (Obs.: if someone can teach me how to better organize the code, also thank you.

public class CadastroServicos extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    EditText numeroPedido;
    Spinner nomeParceiroServico;
    Spinner tipoServicoServico;
    EditText cliente;
    EditText produto;
    EditText quantidade;
    EditText precoPago;
    EditText dataEnvio;
    ArrayList<String> item;

    DatabaseReference dbReferenceParceiro;
    DatabaseReference dbReferenceServico;

    ValueEventListener listenerParceiro;
    ValueEventListener listenerServico;

    ArrayAdapter<String> adapterParceiro;
    ArrayAdapter<String> adapterServico;

    ArrayList<String> spinnerListParceiro;
    ArrayList<String> spinnerListServico;


    FirebaseDatabase firebaseDatabase;
    DatabaseReference databaseReference;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cadastro_servicos);

        numeroPedido = findViewById(R.id.editNumeroPedido);
        nomeParceiroServico = findViewById(R.id.spinnerParceiro);
        tipoServicoServico = findViewById(R.id.spinnerTipoServico);
        cliente = findViewById(R.id.editCliente);
        produto = findViewById(R.id.editProduto);
        quantidade = findViewById(R.id.editQuantidade);
        precoPago = findViewById(R.id.editPrecoPago);
        dataEnvio = findViewById(R.id.editDataEnvio);


        dbReferenceParceiro = FirebaseDatabase.getInstance().getReference("Parceiro");
        spinnerListParceiro = new ArrayList<>();
        adapterParceiro = new ArrayAdapter<String>(CadastroServicos.this, android.R.layout.simple_spinner_dropdown_item, spinnerListParceiro);


        dbReferenceServico = FirebaseDatabase.getInstance().getReference("TipoServico");
        spinnerListServico = new ArrayList<>();
        adapterServico = new ArrayAdapter<String>(CadastroServicos.this, android.R.layout.simple_spinner_dropdown_item, spinnerListServico);

        ArrayAdapter adapter = new ArrayAdapter<String>(CadastroServicos.this, android.R.layout.simple_spinner_dropdown_item, spinnerListParceiro);

        nomeParceiroServico.setAdapter(adapterParceiro);
        tipoServicoServico.setAdapter(adapterServico);


        retrieveData();
        inicializaFirebase();
        inicializaFirebase2();

    }