Questions[listview]

I have an interface with a ListView, each element has a PopupMenuButtonwith an option, this option sends information to another screen

layout of the widget where thePopupMenuButton

class _PruebaPantallaState extends State<PruebaPantalla> {
  int count = 0;
  @override
  Widget build(BuildContext context) {
    print("6.-Pantalla prueba");
    // TODO: implement build
    return Scaffold(
      body: getApidataList(),
    );
  }
  FutureBuilder getApidataList() {
    return FutureBuilder(
      future: ApiService.getdataList(),
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {
          print("3.-Entrada (conexion establecida)");
          final data = snapshot.data;
          return ListView.separated(
            separatorBuilder: (context, index) {
              return Divider(
                height: 2,
                color: Colors.black,
              );
            },
            itemBuilder: (context, index) {
              return ListTile(
                title: Text(
                  data[index]['dataTitulo'].toString(),
                  style: TextStyle(
                      color: Colors.black, fontWeight: FontWeight.bold),
                ),
                subtitle: Text(data[index]['dataTextoBiblico'].toString()),
                onTap: () {
                  datadb datadb =
                      datadb("", 0, 0, "", "", "", "", "", "", "", 0);
                  datadb.setdataId = data[index]["dataId"];
                  datadb.setdataTipo = data[index]["dataTipo"];
                  datadb.setdataNum = data[index]["dataNum"];
                  datadb.setdataNumMasc = data[index]["dataNumMasc"];
                  datadb.setdataTitulo = data[index]["dataTitulo"];
                  datadb.setdataContenido = data[index]["dataContenido"];
                  datadb.setdataPartitura = data[index]["dataPartitura"];
                  datadb.setdataTextPublic =
                      data[index]["dataTextoBiblico"];
                  datadb.setdataDatosPublic =
                      data[index]["dataDatosComplementarios"];
                  datadb.setdataNota = data[index]["dataNota"];
                  datadb.setdataFechaActualizacion =
                      data[index]["dataFechaActualizacion"];
                  datadb.setdataStatus = 1;
                  navigateToDetail(datadb);
                },
                trailing: PopupMenuButton<dynamic>(
                    onSelected: showMenuSelection,
                    itemBuilder: (context) => [
                          PopupMenuItem(
                            child: Text("Agregar a mis listas"),
                            value: data[index],
                          )
                        ]),
              );
            },
            itemCount: data.length,
          );
        }
        return Center(
          child: CircularProgressIndicator(),
        );
      },
    );
  }


  void navigateToDetail(datadb data) async {
    bool result =
        await Navigator.push(context, MaterialPageRoute(builder: (context) {
      return dataDetalle(todo: data);
    }));
  }


  void showMenuSelection(dynamic value) async {
    bool result = await Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => Play_List(value),
      ),
    );
    if (result) {
      print('>>>>>>>>>>>>>>Mostrando SnackBar<<<<<<<<<<<<');
      final snackBar = SnackBar(
        content: Text('Se agrego correctamente a la lista'),
      );
      Scaffold.of(context).showSnackBar(snackBar);
      print(
          "Se agrego correctamente a la lista--------------------------------");
    }
  }

  void updateListView() {
    final Future<Database> dbFuture = databaseHelper.initializeDatabase();
    dbFuture.then((databse) {
      Future<List<datadb>> dataListFuture = databaseHelper.getdataList();
      dataListFuture.then((dataList) {
        setState(() {
          this.dataList = dataList;
          this.count = dataList.length;
        });
      });
    });
  }
}

This part is where you are redirected to another screen

trailing: PopupMenuButton<dynamic>(
    onSelected: showMenuSelection,
    itemBuilder: (context) => [
          PopupMenuItem(
             child: Text("Agregar a mis listas"),
             value: data[index],
          )
    ]),

MethodshowMenuSelection Which is supposed to receive a type value on return boolto display aSnackBar

void showMenuSelection(dynamic value) async {
    bool result = await Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => Play_List(value),
      ),
    );
    if (result) {
        final snackBar = SnackBar(
            content: Text('Se agrego correctamente a la lista'),
        );
        setState(() {
            Scaffold.of(context).showSnackBar(snackBar);
        });
    }
}

If I remove the setStateit sends me the following exception in the same way I try to use a showDialogand it sends the same exception

_AssertionError ('package:flutter/src/material/scaffold.dart': Failed assertion: line 1184 pos 12: 'context != null': is not true.)

If I put the setStateit sends me the following exception

FlutterError (setState() called after dispose(): _PruebaPantallaState#d31fe(lifecycle state: defunct, not mounted) This error happens if you call setState() on a State object for a widget that no longer appears in the widget tree (eg, whose parent widget no longer includes the widget in its build).This error can occur when code calls setState() from a timer or an animation callback.The preferred solution is to cancel the timer or stop listening to the animation in the dispose() callback.Another solution is to check the "mounted" property of this object before calling setState() to ensure the object is still in the tree.This error might indicate a memory leak if setState() is being called because another object is retaining a reference to this State object after it has been removed from the tree.To avoid memory leaks, consider breaking the reference to this object during dispose().)

To return after adding to the other interface I use the following method The method contains much more information but I don't think it is necessary to include it since the one that returns to the interface is only one line. In case all the information is required, I can add it.

void navigateToDetail(dynamic lista, BuildContext newContext) async {
    Navigator.pop(context,true);
}

I try to place a dividing line between each item ListViewthat is filled with the elements of an Array being as follows

body: ListView(
    children: litems
        .map((data) => ListTile(
              title: Text(data),
              trailing: PopupMenuButton(
                  onSelected: removeItemSelecteMenu,
                  icon: Icon(Icons.delete),
                  itemBuilder: (context) => [
                        PopupMenuItem(
                          value: data,
                          child: Text("Eliminar"),
                        )
                      ]),
            ))
        .toList(),
  ),

I try to do it the following way

body: ListView(
    children: litems
        .map((data) => ListTile.divideTiles(
          context: context,
              title: Text(data),
              trailing: PopupMenuButton(
                  onSelected: removeItemSelecteMenu,
                  icon: Icon(Icons.delete),
                  itemBuilder: (context) => [
                        PopupMenuItem(
                          value: data,
                          child: Text("Eliminar"),
                        )
                      ]),
            ))
        .toList(),
  ),

but it sends me an error in the following lines or code

children: litems

title:

trailing:

when going to review the error children: litemsshows me the following

The argument type 'List<Iterable<Widget>>' can't be assigned to the parameter type 'List<Widget>'

I am making an application in which by selecting the ListViewI can send the data using the following method

onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => HimnoDetalle(todo: Himnoslista[index]),
            ),
          );
        },

But I have added one PopupMenuButtonwhich at the moment has 2 options, both buttons send to different interfaces I did it in the following way

trailing: PopupMenuButton<String>(
          onSelected: _choiceAction,
          itemBuilder: (BuildContext context) {
            return Constants.choices.map((String choice) {
              return PopupMenuItem<String>(
                value: choice,
                child: Text(choice),
              );
            }).toList();
          },
        )

where _choiceAction is a method within the same class declared as follows

void _choiceAction(String choice) {
if (choice == Constants.agregarPlay) {
  Navigator.pushNamed(context, "/Play_List");
} else if (choice == Constants.agregarFavorit) {
  Navigator.pushNamed(context, "/Registro");
}

}

But my intention is to send the name to the interface that you specify depending on the selection thePopupMenuButton

I tried to add the following method inside the PopupMenuButtonbut it gives me errors... my Listviewcomplete is as follows

body: ListView.builder(
    itemCount: Himnoslista.length,
    itemBuilder: (context, index) {
      return ListTile(
        title: Text(Himnoslista[index].tituloHimno),
        // Cuando un usuario pulsa en el ListTile, navega al DetailScreen.
        // Tenga en cuenta que no solo estamos creando un DetailScreen,
        // también le pasamos el objeto Todo actual!
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => HimnoDetalle(todo: Himnoslista[index]),
            ),
          );
        },
        trailing: PopupMenuButton<String>(
          onSelected:  Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => HimnoDetalle(todo: Himnoslista[index]),
            ),
          ),
          itemBuilder: (BuildContext context) {
            return Constants.choices.map((String choice) {
              return PopupMenuItem<String>(
                value: choice,
                child: Text(choice),
              );
            }).toList();
          },
        ),
      );

But it gives me an error in the following lines that are where the selection of the element of thePopupMenuButton

onSelected:  Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => HimnoDetalle(todo: Himnoslista[index]),
            ),
          ),

I have found a code for a listview with images on this page: http://cursoandroidstudio.blogspot.com.es/2014/07/listview-con-imagenes.html I need it to work with bitmap type, I have changed everything of the type int[] to Bitmap[] . The result is as follows:

public class MainActivity extends AppCompatActivity {

ListViewAdapter adapter;

String[] titulo = new String[]{
        "titulo1",
        "titulo2",
        "titulo3",
        "titulo4",
};

Bitmap[] imagenes = {
        BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher),
        BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher),
        BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher),
        BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher)
};

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

    final ListView lista = (ListView) findViewById(R.id.listView1);
    adapter = new ListViewAdapter(this, titulo, imagenes);
    lista.setAdapter(adapter);

    }
}



public class ListViewAdapter extends BaseAdapter {
// Declare Variables
Context context;
String[] titulos;
Bitmap[] imagenes;
LayoutInflater inflater;

public ListViewAdapter(Context context, String[] titulos, Bitmap[] imagenes) {
    this.context = context;
    this.titulos = titulos;
    this.imagenes = imagenes;
}

@Override
public int getCount() {
    return titulos.length;
}

@Override
public Object getItem(int position) {
    return null;
}

@Override
public long getItemId(int position) {
    return 0;
}

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

    // Declare Variables
    TextView txtTitle;
    ImageView imgImg;

    //http://developer.android.com/intl/es/reference/android/view/LayoutInflater.html
    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    View itemView = inflater.inflate(R.layout.list_row, parent, false);

    // Locate the TextViews in listview_item.xml
    txtTitle = (TextView) itemView.findViewById(R.id.list_row_title);
    imgImg = (ImageView) itemView.findViewById(R.id.list_row_image);

    // Capture position and set to the TextViews
    txtTitle.setText(titulos[position]);
    imgImg.setImageBitmap(imagenes[position]);

        return itemView;
    }
}

But it doesn't work for me, does anyone know why or how I can fix it?