Since good people of Google are saying that this is `as intended`
here's an ugly brutal way of dealing with this problem that works for
me. Basically the assumption here is that as events are issued I
compare last saved first item index with one that is passed in the
`onScroll` call. I will only process event if these do not match:
this.view.setOnScrollListener(new OnScrollListener() {
private int lastSavedFirst = -1;
@Override
public void onScroll(final AbsListView view, final int
first, final int visible, final int total) {
// detect if last item is visible
if (visible < total && (first + visible == total)) {
// only process first event
if (first != lastSavedFirst) {
lastSavedFirst = first;
Log.d("OnScrollListener - end of list", "fvi:
" + first + ", vic: " + visible + ", tic: "
+ total);
onLastListItemDisplayed(total, visible);
}
}
}
@Override
public void onScrollStateChanged(final AbsListView view,
final int scrollState) {
// Log.d("OnScrollListener", "state: " + scrollState);
}
});
On Oct 13, 11:58 am, "droidin.net" <[email protected]> wrote:
> In my app I have a ListView backed by ArrayAdapter. In it I'm
> detecting events in OnScrollListener#onScroll method to find end of
> the list. I noticed that on the phone (MyTouch) both track-ball and
> gesture/touch scrolling will trigger the event twice. On the emulator
> I get the same behavior with a scrolling wheel and click-and-drug
> scrolling. However in emulator if I use down-arrow button to scroll
> the event is fired only once.
>
> Here's the code:
>
> this.view.setOnScrollListener(new OnScrollListener() {
> @Override
> public void onScroll(final AbsListView view, final int first,
> final int visible, final int
> total) {
> // detect if last item is visible
> if (visible < total && (first + visible == total)) {
> Log.d("OnScrollListener - end of list", "fvi: " +
> first + ", vic: " + visible + ", tic: " + total);
> // this line gets called twice
> onLastListItemDisplayed(total, visible);
> }
> }
> }
>
> How do I suppress or handle this behavior? I need just a single event
> and trying not to revert to silly hacks such as boolean field.
>
> As far as I can tell - both events have identical stacktrace
>
> Thread [<3> main] (Suspended (breakpoint at line 116 in
> SearchResultsView$4))
> SearchResultsView$4.onScroll(AbsListView, int, int, int) line:
> 116
> ListView(AbsListView).invokeOnItemScrollListener() line: 655
> ListView.arrowScrollImpl(int) line: 2256
> ListView.arrowScroll(int) line: 2172
> ListView.commonKey(int, int, KeyEvent) line: 1977
> ListView.onKeyMultiple(int, int, KeyEvent) line: 1929
> KeyEvent.dispatch(KeyEvent$Callback) line: 899
> ListView(View).dispatchKeyEvent(KeyEvent) line: 3647
> ListView(ViewGroup).dispatchKeyEvent(KeyEvent) line: 744
> ListView.dispatchKeyEvent(KeyEvent) line: 1909
> FrameLayout(ViewGroup).dispatchKeyEvent(KeyEvent) line: 746
> LinearLayout(ViewGroup).dispatchKeyEvent(KeyEvent) line: 746
> PhoneWindow$DecorView(ViewGroup).dispatchKeyEvent(KeyEvent) line:
> 746
> PhoneWindow$DecorView.superDispatchKeyEvent(KeyEvent) line: 1708
> PhoneWindow.superDispatchKeyEvent(KeyEvent) line: 1197
> SearchResultsView(Activity).dispatchKeyEvent(KeyEvent) line:
> 1967
> PhoneWindow$DecorView.dispatchKeyEvent(KeyEvent) line: 1684
> ViewRoot.deliverKeyEventToViewHierarchy(KeyEvent, boolean) line:
> 2329
> ViewRoot.handleFinishedEvent(int, boolean) line: 2299
> ViewRoot.handleMessage(Message) line: 1621
> ViewRoot(Handler).dispatchMessage(Message) line: 99
> Looper.loop() line: 123
> ActivityThread.main(String[]) line: 4203
> Method.invokeNative(Object, Object[], Class, Class[], Class, int,
> boolean) line: not available [native method]
> Method.invoke(Object, Object...) line: 521
> ZygoteInit$MethodAndArgsCaller.run() line: 791
> ZygoteInit.main(String[]) line: 549
> NativeStart.main(String[]) line: not available [native method]
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