我正在尝试在AppWidget中将ListView滚动到特定位置。
但它没有做任何事情，我还尝试了setPosition方法，但也不起作用。
同时没有错误或堆栈跟踪。
代码：
if (list.size() == 0) {
loadLayout(R.layout.rooster_widget_header);
views.addView(R.id.header_container,
views);
} else {
views.setRemoteAdapter(R.id.lvWidget, svcIntent);
views.setScrollPosition(R.id.lvWidget, 3);
}
问题：在显示之前，ListView没有任何子项。因此，在设置适配器后立即调用setScrollPosition无效。以下是在AbsListView中执行此检查的代码：
final int childCount = getChildCount();
if (childCount == 0) {
// Can't scroll without children.
return;
}
解决方案: 理想情况下，我会使用 ViewTreeObserver.OnGlobalLayoutListener 来设置 ListView 的滚动位置，但是在远程视图中不可能。通过一个带有延迟的可运行程序来设置滚动位置并调用 partiallyUpdateAppWidget。我已经修改了 Android 天气小部件代码，并在 git hub 上分享。
public class MyWidgetProvider extends AppWidgetProvider {
private static HandlerThread sWorkerThread;
private static Handler sWorkerQueue;
public MyWidgetProvider() {
// Start the worker thread
sWorkerThread = new HandlerThread("MyWidgetProvider-worker");
sWorkerThread.start();
sWorkerQueue = new Handler(sWorkerThread.getLooper());
}
public void onUpdate(Context context, final AppWidgetManager appWidgetManager, int[] appWidgetIds) {
for (int i = 0; i < appWidgetIds.length; ++i) {
...
final RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
views.setRemoteAdapter(R.id.lvWidget, svcIntent);
sWorkerQueue.postDelayed(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
views.setScrollPosition(R.id.list, 3);
appWidgetManager.partiallyUpdateAppWidget(appWidgetIds[i], views);
}
}, 1000);
appWidgetManager.updateAppWidget(appWidgetIds[i], views);
...
}
}
}
我认为我有解决方案，我在自己的代码中使用它。 顺便提一下，我有一些页面并希望按需显示它们：
getListView().setSelection(((moreServices-1)*20)+1);
对于你来说，这将是：
yourListView.setSelection(3);
希望能有所帮助...
编辑
我认为你应该看看那个... 那是老的，但也许从未改变过
setRelativeScrollPosition(int viewId, int offset) 吗？ - SiddsmoothScrollToPosition (int position, int boundPosition) 呢？ - SiddappWidgetManager.updateAppWidget(widgetId, remoteViews);
如果我们没有直接访问 AppWidgetManager 的方式，那么还有第二种方法。
/**
* Refresh the views on the widget
* NOTE: Use only in case we dont have direct acces to AppWidgetManager
*/
private void invalidateWidget() {
ComponentName widget = new ComponentName(this, YourWidgetProvider.class);
AppWidgetManager manager = AppWidgetManager.getInstance(this);
manager.updateAppWidget(widget, mRv);
}
这样更改应该会反映在小部件中。如果这不起作用，我需要更多细节来找出问题并编辑此答案。希望能有所帮助。
两件事：
views.setScrollPosition(R.id.lvWidget, 3);
是正确的调用。在内部，setScrollPosition(int, int) 调用了 RemoteViews＃setInt(viewId，"smoothScrollToPosition"，position);。
viewId : your ListView's id
"smoothScrollToPosition" : method name to invoke on the ListView
position : position to scroll to
所以，你正在调用正确的方法。
以下是对方法AppWidgetManager#partiallyUpdateAppWidget(int, RemoteViews)的注释 - 取自AppWidgetManager.java的源代码。我相信它可以回答你的问题：...与{RemoteViews#showNext(int)}，{RemoteViews#showPrevious(int)}，{RemoteViews#setScrollPosition(int, int)}和类似命令一起使用...
/**
* Perform an incremental update or command on the widget specified by appWidgetId.
*
* This update differs from {@link #updateAppWidget(int, RemoteViews)} in that the RemoteViews
* object which is passed is understood to be an incomplete representation of the widget, and
* hence is not cached by the AppWidgetService. Note that because these updates are not cached,
* any state that they modify that is not restored by restoreInstanceState will not persist in
* the case that the widgets are restored using the cached version in AppWidgetService.
*
* Use with {RemoteViews#showNext(int)}, {RemoteViews#showPrevious(int)},
* {RemoteViews#setScrollPosition(int, int)} and similar commands.
*
* <p>
* It is okay to call this method both inside an {@link #ACTION_APPWIDGET_UPDATE} broadcast,
* and outside of the handler.
* This method will only work when called from the uid that owns the AppWidget provider.
*
* <p>
* This method will be ignored if a widget has not received a full update via
* {@link #updateAppWidget(int[], RemoteViews)}.
*
* @param appWidgetId The AppWidget instance for which to set the RemoteViews.
* @param views The RemoteViews object containing the incremental update / command.
*/
public void partiallyUpdateAppWidget(int appWidgetId, RemoteViews views) {
partiallyUpdateAppWidget(new int[] { appWidgetId }, views);
}
正如注释所示，在views.setScrollPosition(R.id.lvWidget, 3)之后调用partiallyUpdateAppWidget(appWidgetId, views)。
注释还警告您：如果小部件没有通过{#updateAppWidget(int[], RemoteViews)}接收到完整的更新，则将忽略此方法。这可能意味着以下调用：
views.setRemoteAdapter(R.id.lvWidget, svcIntent);
views.setScrollPosition(R.id.lvWidget, 3);
不应该在一个更新中完成。我建议您将这些调用分成两个单独的更新：
首先：
views.setRemoteAdapter(R.id.lvWidget, svcIntent);
mAppWidgetManager.updateAppWidget(appWidgetIds, views);
第二点：
views.setScrollPosition(R.id.lvWidget, 3);
mAppWidgetManager.partiallyUpdateAppWidget(appWidgetId, views);