How to know when an Android ListView is done being populated

Question

I have a child Activity that contains a ListView. This Activity is populated asynchronously from a SQLite cursor. The list items contain a TextView, a RadioButton, and a normal Button. The XML is shown below:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/rlCategoryListItemLayout" xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content">
 <TextView android:id="@+id/tvCategoryListItemTitle" style="@style/uwLargeListItemLabelStyle" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_centerVertical="true" android:singleLine="true" android:text="This is a test note title" />
 <LinearLayout android:orientation="horizontal" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentRight="true" android:gravity="center_vertical">
  <RadioButton android:id="@+id/rdoCategoryListItemSelect" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_marginRight="10dip" />
  <Button android:id="@+id/btnCategoryListItemDelete" android:background="@drawable/delete_red" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" />
 </LinearLayout>
</RelativeLayout>

I have to do some logic to determine which RadioButton is selected by default, and I can't do it until the ListView is already loaded. The problem is that with all the events I have tried so far (onCreate, onPostCreate, onResume, onWindowFocusChanged), the ListView child count is zero. I've also tried using the getView method in the ArrayAdapter class, but that method is called mutliple times and the ListView child count is potentially different every time, leading to unexpected results. Apparently, these events are firing before the ListView has finished being completely populating with its child items.

Is there an event I can listen for, or some other way to determine when the ListView is finished populating and has all of its children accessible to be modified programmatically?

Thank you!

Answer 1

A ListView does not actually create a View for each element in the list of data it is rendering. Instead, it recycles views in order to be responsive and not hog memory. You might rethink what you really need when you say the ListView needs to be populated.

It might help if you go into a little more detail about your app and post some code.

Answer 2

At the end of your asynchronous work on the database, you can use Handler.post(Runnable) to run code back on the main thread. Its almost like triggering a callback and you can guarantee that it will run after the list is populated. You can even schedule the Runnable to occur at a certain time later if you need to time everything very carefully.

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