Data sent from one Activity to another arrives null

Question

My Activity I’m displaying the database data in listview

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

    final ListView listView = (ListView) findViewById(R.id.lvItems);


    GenericDAO g = new GenericDAO(getApplicationContext());
    ArrayList<Cliente> cArray = g.getClientes();

    final List<String> itens = new ArrayList();

    for (int i = 0; i < cArray.size() ; i++) {
        Cliente c = new Cliente();
        c = cArray.get(i);
        itens.add(c.getNome());
    }

    ArrayAdapter<String> itemsAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, itens);
    listView.setAdapter(itemsAdapter);

    //inserindo evento de click no listView e enviando os dados para a segunda activity

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> adapter, View view,
                                int posicao, long id) {

            long cli = adapter.getItemIdAtPosition(posicao);
            Intent it = new Intent(getBaseContext(), Tela_Emprestimo.class);
            it.putExtra("idCliente", cli);

            startActivityForResult(it, 1);
        }
    });

my second Activity where I’m getting the data, only I’m not getting the customer’s name

public class Tela_Emprestimo extends AppCompatActivity implements Serializable{
    Cliente cliente;
    TextView txtCliente;

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

        Intent i = getIntent();
        cliente = (Cliente)i.getSerializableExtra("idCliente");
        Toast.makeText(this, "cliente :" + cliente.getNome(), Toast.LENGTH_LONG).show();    
    }
}

The Customer class

public class Client Implements Serializable { int private id; private string name; Private String street; Private String neighborhood; private string number; private int idcidade; private int idFunctionary;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getNome() {
    return nome;
}

public void setNome(String nome) {
    this.nome = nome;
}

public String getRua() {
    return rua;
}

public void setRua(String rua) {
    this.rua = rua;
}

public String getBairro() {
    return bairro;
}

public void setBairro(String bairro) {
    this.bairro = bairro;
}

public String getNumero() {
    return numero;
}

public void setNumero(String numero) {
    this.numero = numero;
}

public int getIdcidade() {
    return idcidade;
}

public void setIdcidade(int idcidade) {
    this.idcidade = idcidade;
}

public int getIdFuncionario() {
    return idFuncionario;
}

public void setIdFuncionario(int idFuncionario) {
    this.idFuncionario = idFuncionario;
}

Answer 1

What you are to include in Extra is a long, I suppose the Customer ID, not the Customer(object).
When trying to do, in Activity Tela_loan, the cast for Client

cliente = (Cliente)i.getSerializableExtra("idCliente"); 

the result is null;

See how you’re doing:

long cli = adapter.getItemIdAtPosition(posicao);
Intent it = new Intent(getBaseContext(), Tela_Emprestimo.class);
it.putExtra("idCliente", cli);

If you want to pass a Customer, you must have a method in the Adapter that returns one, something like Cliente getItemAtPosition(posicao){...}.

The code would look like this:

Cliente cli = adapter.getItemAtPosition(posicao);
Intent it = new Intent(getBaseContext(), Tela_Emprestimo.class);
it.putExtra("idCliente", cli);

For everything to work as it was said, you need to use a custom Adapter that can handle Customer-type objects.

Alternatively, since the list only uses the client name, use a ArrayList<Cliente>, do the override of the method toString() of the Customer class and get the Customer of the item clicked on the method onClick() as follows: Cliente cli = (Cliente)parent.getAdapter().getItem(position);.
See an example on this reply.

_{The Client class should implement the interface Serializable, it would be preferable that she implement Parcelable.}

Answer 2

As you are using this way to add the data to Intent, using the client name will be easier to recover

String cli = adapter.getItemIdAtPosition(posicao);//Pega o nome do cliente da lista, pois vc populou a lista com um List de nomes dos clientes
Intent it = new Intent(getBaseContext(), Tela_Emprestimo.class);
it.putExtra("idCliente", cli);//Adiciona o nome do cliente a Intent

The variable cli is a String of the client name, in the following Activity you should search for a String, like this:

Intent i = getIntent();
String clienteName = i.getStringExtra("idCliente"); //Aqui vc tem o nome do cliente

And then just instantiate your research class in the bank and create a method to catch the customer from the name you received at Activity

GenericDAO g = new GenericDAO(this);//usar this se estiver em uma activity
Cliente cli = g.getClienteByNome(clienteName);