Question

In my application I am trying to use a ListView inside a PopupDialog. This is done inside of an AsyncTask. I think the issue lies somewhere between the onPreExecute and onPostExecute…..everything is returning correctly, but the list = null after I use findViewById(). I can’t figure out why……Note, the AsyncTask and Adapter are both inner classes.

    protected void onPreExecute() {
        AlertDialog.Builder alert = new AlertDialog.Builder(CreateNewReport.this);
        LayoutInflater inflater = LayoutInflater.from(CreateNewReport.this);
        popupView = inflater.inflate(R.layout.add_expenses, null);

        alert.setTitle("Add Expenses").setView(popupView);

        alert.setNeutralButton("Save", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {

            }
        });

        alert.show();
    }

    protected void onPostExecute(List<Expense> expenses){
        availableExpenses = expenses;

        // create list adapter for available expenses
        ArrayAdapter<Expense> adapter = new ArrayAdapter<Expense>(CreateNewReport.this,
                android.R.layout.simple_list_item_1, expenses);

        // get a reference to the list
        final ListView list = (ListView) findViewById(R.id.listViewAvailableExpenses);

        // set the list adapter
        list.setAdapter(adapter);

        // find widgets
        final ProgressBar progress = (ProgressBar) findViewById(R.id.loading_expenses);
        final LinearLayout listLayout = (LinearLayout) findViewById(R.id.available_expenses);
        final LinearLayout progressContainer = (LinearLayout) findViewById(R.id.available_expenses_loading);

        // change visibility as needed
        progressContainer.setVisibility(View.INVISIBLE);
        progress.setVisibility(View.INVISIBLE);
        listLayout.setVisibility(View.VISIBLE);
    }

XML for the popup box

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <ProgressBar
         android:id="@+id/loading_expenses"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         style="@android:style/Widget.ProgressBar.Large"
         android:layout_centerInParent="true"
         />
        <ListView
            android:id="@+id/listViewAvailableExpenses"
            style="@style/Container"
            android:cacheColorHint="#00000000"
            />
</RelativeLayout>

Answer 1

That’s because the findViewById() call is looking for your list inside the Activity (it’s a method of the Activity instance), but your list is inside the dialog. Instead, you need to save a reference to the dialog and then do theDialog.findViewById(R.id.ListNote):

//PreExecute
theDialog = alert.create(); //theDialog is an instance variable of the asynctask
theDialog.show();


//PostExecute
final ListView list = (ListView) theDialog.findViewById(R.id.ListNote);