List data in an Activity

This is my first posting on the forum, I hope I am not inflicting any rules. I'm starting in Android programming, so I'm trying to develop a CRUD . So far I've done the registration and listing, but the latter insists on making the code even seemingly correct ... (Consistent with instructions from sites like DevMidia). I would like help finding what I am doing wrong, thank you in advance! :)

BANK CLASS CODE:

public class Banco extends SQLiteOpenHelper{

static final String NOME_BANCO = "banco.db";
static final String TABELA = "pacientes";

static final String ID = "id";
static final String PACIENTE = "paciente";
static final String LEITO = "leito";

static final int VERSAO = 1;


public Banco(Context context) { // local do banco

    super(context,NOME_BANCO, null, VERSAO);

}

@Override

public void onCreate(SQLiteDatabase db) {
    db.execSQL("" +
            "create table pacientes(id integer primary key autoincrement, paciente text not null" +
            ", leito text not null);");
}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS pacientes");
    onCreate(db);
}

CRUD CODE

public class CRUD {

 SQLiteDatabase db;
 Banco banco;

public CRUD (Context context){
            banco = new Banco(context);
}

public String insert(String paciente, String leito){
    //responsável por inserir
    ContentValues valores;
    long resultado;

    db=banco.getWritableDatabase();

    //gravar no banco
    valores = new ContentValues();
    valores.put(Banco.PACIENTE, paciente);
    valores.put(Banco.LEITO, leito);

    resultado = db.insert(Banco.TABELA, null, valores);
    db.close();
    if (resultado ==-1)
        return "Erro ao inserir registro";
    else
        return "Cadastrado :)";
}

public Cursor carregaDados(){
    Cursor cursor;
    String campos[] = {banco.PACIENTE,banco.LEITO,banco.ID};

    db = banco.getReadableDatabase();
    cursor = db.query(banco.TABELA, campos, null, null, null, null, null, null);

    if(cursor!=null)
    {
        cursor.moveToFirst();
    }
    db.close();

    return cursor;
}

DATA LISTING CODE

public class Consulta extends AppCompatActivity {

ListView lista;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_consulta);

    CRUD crud = new CRUD (getBaseContext());
    Cursor cursor = crud.carregaDados();

    String [] nomecampos = new String [] {Banco.PACIENTE, Banco.LEITO,Banco.ID};

    int [] idViews = new int [] {R.id.idPaciente, R.id.idLeito,R.id.idId};

    SimpleCursorAdapter adaptador = new SimpleCursorAdapter(getBaseContext(),
            R.layout.formatador, cursor, nomecampos,idViews,0);
    lista = (ListView)findViewById(R.id.listinha);
    lista.setAdapter(adaptador);
}
}