Question

I’m learning Android and I’ve done a custom control. When I put it in a Layout, it works fine. I put it in this way in itemduplicados.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <com.android.customViews.CtlDuplicado
        android:id="@+id/dupCancion"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

Then I want to do a list of many of this controls, so I use a listview in listadoduplicado.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LstListadoDuplicados"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

</ListView>
</LinearLayout>

An Activity for this with a onCreate:

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.listadoduplicados);
        AdaptDuplicados adapter = new AdaptDuplicados(this, Deduplicator.deduplicate());
        final ListView lstDuplicados = (ListView) findViewById(R.id.LstListadoDuplicados);
        lstDuplicados.setAdapter(adapter);
        lstDuplicados.setVisibility(View.VISIBLE);

    }

And then a class that extends arrayadapter to populate the listview with ctlduplicados:

public AdaptDuplicados(Activity context, ArrayList<Duplicado> datos) {
    super(context, R.layout.itemduplicado, datos);
        this.context = context;
        this.datos = datos;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
                View item = convertView;
                DuplicadoViewHolder dvh;
                if (item == null){
                    LayoutInflater li = context.getLayoutInflater();
                    item = li.inflate(R.layout.itemduplicado, null);
                    dvh = new DuplicadoViewHolder();
                    dvh.duplicado = (CtlDuplicado)item.findViewById(R.id.dupCancion);
                    item.setTag(item);
                }else{
                    dvh = (DuplicadoViewHolder)item.getTag();
                }
                dvh.duplicado.setCanciones(datos.get(position));//here is the nullpointerexception cause duplicado is null
                return (item);
            }

Well, the I have a nullpointerexception because dvh.duplicado is null.

Debbuging in eclipse I see that in the line

item = li.inflate(R.layout.itemduplicado, null); 

The item is created and item contains a CtlDuplicado well created in an internal array called mChildren, but when I get item.findViewById(R.id.dupCancion) it returns null…

The R.id.dupCancion is defined in project’s R.

Can someone give me any clue of what is happening?

EDIT: the dvh.duplicado that is null is the one in the ‘if’, this;

 dvh.duplicado = (CtlDuplicado)item.findViewById(R.id.dupCancion);

R.id.dupCancion exists and there is a CtlDuplicado created in item’s internal array called mChildren but when I call findViewById in item it returns null…

Actualization:

I tried to access the controls inside my custom control and I can reach them in this way:

lbltxt1 = (TextView)item.findViewById(R.id.lbltxt1);
lbltxt2 = (TextView)item.findViewById(R.id.lbltxt2);
lblSubtxt1 = (TextView)item.findViewById(R.id.lblSubtxt1);

With item coming from the ‘if’…

So I can reach the components of my control but not the control itself…

The CtlDuplicado is created (I have reach to the constructor via debugger) its drawed properly but then I cannot access it via findViewById… but I can access their components via that function… Ufff…

Answer 1

You are not setting the actual view (probably a typo)

item.setTag(item);

should be

item.setTag(dvh);