Thanks Romain, getView is now called for each row only once.
Just one follow up question:
it seems that I am having a problem with the listviewadapter.
resultsList = (ListView) this.findViewById(R.id.list);
resultsList.setAdapter(new ResultsListAdapter(this,R.layout.row,
currentSearch));
In my getView I am doing a request for each row to get the thumbnail
image in a different thread:
if (record.getImgURL().equals("none"))
holder.thumbView.setImageResource(R.drawable.nothumb);
else
{
String url = item.getImgURL();
makeRequest(position,url,null,false);
}
and handling the response from makeRequest()
@Override
public void onResponseCompleted(boolean success, int userId, int
ticket, Request request) {
if (success)
{
...
ViewHolder holder =
(ViewHolder)resultsList.getChildAt(userId).getTag();
This works fine for the first 5 records, then this last line throws a
null pointer exception because for some reason, even though the
getview is called on the row represented by
resultsList.getChildAt(userId) - which it must to call makeRequest
anyway - the view hasn't been added to resultsList.
Why is this happening? There are no convertViews yet / The screen fits
4 rows and I can scroll down to the fifth and it works fine, just the
sixth row that isn't added to the resultsList.
On Apr 14, 5:26 pm, Romain Guy <romain...@android.com> wrote:
> This is not an issue, there is absolutely no guarantee on the order in
> which getView() will be called nor how many times. In your particular
> case you are doing the worst thing possible with a ListView by giving
> it a height=wrap_content. This forces ListView to measure a few
> children out of the adapter at layout time, to know how big it should
> be. This is what provides ListView with the convertViews you see
> passed to getView() even before you scroll.
>
>
>
> On Tue, Apr 13, 2010 at 1:32 PM, edzah <edzill...@gmail.com> wrote:
> > this is a cross-post from SO . haven't got much attention over there
> > so I am posting it here. orig here:
>
> >http://stackoverflow.com/questions/2618272/custom-listview-adapter-ge...
>
> > ----------------------------------------------------------------------------------
>
> > I have a custom list adapter:
>
> > class ResultsListAdapter extends ArrayAdapter<RecordItem> {
>
> > in the overridden 'getView' method I do a print to check what position
> > is and whether it is a convertView or not:
>
> > �...@override
> > public View getView(int position, View convertView, ViewGroup
> > parent) {
> > System.out.println("getView " + position + " " + convertView);
>
> > The output of this (when the list is first displayed, no user input as
> > yet)
>
> > 04-11 16:24:05.860: INFO/System.out(681): getView 0 null
> > 04-11 16:24:29.020: INFO/System.out(681): getView 1
> > android.widget.relativelay...@43d415d8
> > 04-11 16:25:48.070: INFO/System.out(681): getView 2
> > android.widget.relativelay...@43d415d8
> > 04-11 16:25:49.110: INFO/System.out(681): getView 3
> > android.widget.relativelay...@43d415d8
> > 04-11 16:25:49.710: INFO/System.out(681): getView 0
> > android.widget.relativelay...@43d415d8
> > 04-11 16:25:50.251: INFO/System.out(681): getView 1 null
> > 04-11 16:26:01.300: INFO/System.out(681): getView 2 null
> > 04-11 16:26:02.020: INFO/System.out(681): getView 3 null
> > 04-11 16:28:28.091: INFO/System.out(681): getView 0 null
> > 04-11 16:37:46.180: INFO/System.out(681): getView 1
> > android.widget.relativelay...@43cff8f0
> > 04-11 16:37:47.091: INFO/System.out(681): getView 2
> > android.widget.relativelay...@43cff8f0
> > 04-11 16:37:47.730: INFO/System.out(681): getView 3
> > android.widget.relativelay...@43cff8f0
>
> > AFAIK, though I couldn't find it stated explicitly, getView() is only
> > called for visible rows. Since my app starts with four visible rows at
> > least the position numbers cycling from 0-3 makes sense. But the rest
> > is a mess:
>
> > * Why is getview called for each row three times?
> > * Where are these convertViews coming from when I haven't scrolled
> > yet?
>
> > I did a bit of reseach, and without getting a good answer, I did
> > notice that people were associating this issue with layout issues. So
> > in case, here's the layout that contains the list:
>
> > <?xml version="1.0" encoding="utf-8"?>
> > <LinearLayout xmlns:android="http://schemas.android.com/apk/res/
> > android"
> > android:layout_height="fill_parent"
> > android:layout_width="fill_parent"
> > android:orientation="vertical" >
>
> > <TextView android:id="@+id/pageDetails"
> > android:layout_width="fill_parent"
> > android:layout_height="wrap_content" />
>
> > <ListView android:id="@+id/list"
> > android:layout_width="fill_parent"
> > android:layout_height="wrap_content"
> > android:drawSelectorOnTop="false" />
>
> > </LinearLayout>
>
> > and the layout of each individual row:
>
> > <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/
> > android"
> > android:layout_width="fill_parent"
> > android:layout_height="108dp"
> > android:padding="4dp">
>
> > <ImageView
> > android:id="@+id/thumb"
> > android:layout_width="120dp"
> > android:layout_height="fill_parent"
> > android:layout_alignParentTop="true"
> > android:layout_alignParentBottom="true"
> > android:layout_alignParentLeft="true"
> > android:layout_marginRight="8dp"
> > android:src="@drawable/loading" />
>
> > <TextView
> > android:id="@+id/price"
> > android:layout_width="wrap_content"
> > android:layout_height="18dp"
> > android:layout_toRightOf="@id/thumb"
> > android:layout_alignParentBottom="true"
> > android:singleLine="true" />
>
> > <TextView
> > android:id="@+id/date"
> > android:layout_width="wrap_content"
> > android:layout_height="18dp"
> > android:layout_alignParentBottom="true"
> > android:layout_alignParentRight="true"
> > android:paddingRight="4dp"
> > android:singleLine="true" />
>
> > <TextView
> > android:id="@+id/title"
> > android:layout_width="fill_parent"
> > android:layout_height="wrap_content"
> > android:textSize="17dp"
> > android:layout_toRightOf="@id/thumb"
> > android:layout_alignParentRight="true"
> > android:layout_alignParentTop="true"
> > android:paddingRight="4dp"
> > android:layout_alignWithParentIfMissing="true"
> > android:gravity="center" />
>
> > </RelativeLayout>
>
> > Thank you for your time
>
> > --
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>
> --
> Romain Guy
> Android framework engineer
> romain...@android.com
>
> Note: please don't send private questions to me, as I don't have time
> to provide private support. All such questions should be posted on
> public forums, where I and others can see and answer them
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