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

You can use a Handler to accomplish this task, like this:

In your activity add the Handler as any other property.

private Handler mListViewDidLoadHanlder = new Handler(new Handler.Callback() { 
    @Override
    public boolean handleMessage(Message message) {
        //Do whatever you need here the listview is loaded
        return false;
    }
});

And inside the getView method of your listview adapter you do the comparison to see if the current position is the last one , so , it will finish (just put it before the return):

public View getView(int position, View convertView, ViewGroup parent) {
         //Your views logic here

         if (position == mObjects.size() - 1) {
                mViewDidLoadHanlder.sendEmptyMessage(0);
            }

         return convertView;
     }