I have viewPager() which have 3 pages, it have a recyclerView and each page have three different adapters and i want something like when user clicks on adapter item in first page it adds in a database and second adapter gets its array list from the same database, but it shows in second page's adapter after app restarts, so the question is how to update the second page's adapter without restart.
A regular ListView can use a CursorAdapter which provides some of the functions you need. Alas, there is no existing CursorAdapter class that extends RecyclerView.Adapter.
The quickest solution would be to use RecyclerViewCursorAdapter on GitHub.
Then it would work something like this:
Update your database
Get a reference to your second page fragment. You can store this reference when you create the fragment in getItem(). Note that your fragment could be null depending on what pages the ViewPager has/hasn't created.
Call a method on your fragment that will create a new Cursor to be used by the adapter (with the same query as before). When the adapter receives the new Cursor it will update the RecyclerView.
Related
I have a ListView and an CustomListAdapter that extends CursorAdapter. I'm using a LoaderManager to load the data into my CustomListAdapter when I first load the Fragment containing the ListView. That all works fine. I'm using ContentProviders so any updates or changes to the underlying data in the database are reflected in the Listview.
Now I want to allow the user to search for specific items in the list. So in other words i want to update the list view based on the search query obtains from the SearchDialog. I've got the SearchDialog working and I'm up to the point where I receive the intent in ParentActivity of the ListViewFragment, with the search query. However I'm not really sure what I should be doing now.
I was thinking of detaching and then re-attaching the Fragment to the ParentActivity passing the search query string to the ListViewFragment so that the onCreateLoader() method of the fragment could use the query to do another search. This seemed like an easy way to achieve what I wanted to do.
Is this the correct way to update a ListView based on a search? Or is this overkill for what I'm trying to do? Does anyone have any other suggestions?
Kind Regards
For anyone that wants to know, my requirement changed and instead of using the same Activity to view the results, I sent the results to a new SearchResultActivity that was re-using the ListViewFragment.
I created an instance variable on the ListViewFragement that would store the query string. When creating a new instance of the Fragment, it expects a value for this query string. When I load the Fragment from my first Activity, the string is null and the onCreateLoader() by default loads all the results. When I load the Fragment from SearchResultActivity I pass in the query result from the SearchDialog and the onCreateLoader() will use the query to return a Cursor based on a specific selection.
I didn't need to attach and re-attach the fragment in anyway. However if I was to use the same Activity and ListViewFragment to display the search results, instead of detaching and re-attaching the fragment to the activity, I would probably use the restartLoader method of LoaderManager:
LoaderManager Doc
I have a Fragment that contains a ListView that uses a custom adapter that extends ArrayAdapter. Each item in this list view, contains another ListView that also extends ArrayAdapter. Think of it as a list of news stories and each news story having multiple images.
I now want to add a new image to a news story. What I do is:
ImageAdapter imageAdapter =
newsAdapter.getImageAdapterForNewsItem(id);
imageAdapter.add(imageId);
imageAdapter.notifyDataSetChanged();
This all happens in SelectImagesFragment, where as the news items are listed in the NewsItemsFragment. However, the SelectImagesFragment contains a reference to the NewsItemsFragment. The above code executes in an AsyncTask, and before it executes, I move the user back to the NewsItemsFragment.
I was expecting the news list to get updated, once the AsyncTask completes and the UI to get refreshed. However, this is not happening. Since the ImageAdapter is inside the NewsAdapter, do I need to somehow tell the NewsAdapter that there has been a data change as well? If so, how do I do this? Calling 'notifyDataSetChanged()' won't work, since I didn't modify the underlying list data in NewsAdapter using add().
I have a ListActivity and use a CursorLoader to load the data which is stored in a ContentProvider. I use a custom class extending CursorAdapter to display the list items. In the LoaderCallbacks onLoadFinished I have the following:
public void onLoadFinished(Loader<Cursor> loader, Cursor newCursor) {
cursorAdapter.swapCursor(newCursor);
}
I have a custom layout for the ListActivity which includes a TextView with android:id="#android:id/empty".
The problem is that when I open the application for the first time calling swapCursordoes not refresh the ListView even though there is data to show in the ContentProvider. When I add a new item to the ListView, the list is refreshed properly. However, if I comment out the TextView, which displays a simple text when no data is available, the application works as expected. The swapCursor call automagically updates the ListView accordingly.
Any thoughts on why this occurs or if there is a proper way to do this since I believe calling notifyDataSetChanged won't do the work as the refreshing fails on a very particular case?
You're having this problem because ListActivity automatically sets the empty view (if available) to your ListView.
I'd suggest you try one of these:
Extend activity and after swapCursor call
listView.setEmptyView(findViewById(android.R.id.empty);
Make the empty view gone: android:visibility="gone" and after swapCursor call
findViewById(android.R.id.empty).setVisibility(View.VISIBLE);
#onCreate call listView.setEmptyView(null) and after swapCursor call
listView.setEmptyView(findViewById(android.R.id.empty);
Not sure about all of them, but one of em will certainly work :)
I am trying to display a list fragment in the middle of my activity. The list fragment adapter is a custom adapter (extended from BaseAdapter) with the typical ViewHolder pattern. It is implemented correctly.
I have the adapter set up with greenrobot Eventbus to receive a new List object from an asynctask which does the query in the background (as not to slow down the UI Main Thread).
The problem is the list fragment doesn't have the results of the database query initially so it defaults to empty (and displays the textview in my xml for the main activity which has the id 'empty').
In the end, my adapter, and listviewfragment don't get instaniated at all because it defaults to empty.
Is there a better method to doing this?
How can I get my listview fragment to wait for the data recieved from the asyncTask?
I am going to just do a fragment with a listview in it, instead of a listview fragment, and I'll see if that will help.
As I understood correctly, you did everything okay so far. What you have to do is to add an "update" method to your adapter, and call this whenever your asynctask finished it's job and got the results for you.
This update method should look something like
public void updateAdapterData(List<String> newList) {
mItems.clear(); // say mItems is the global list you have in the adpater
mItems.addAll(newList);
notifyDataSetChanged(); // This will cause the adpater to re-draw it's rows, so now data should be visible in your list
}
And in your fragment you do somehting like:
adpater.updateAdapterData(newList);
Does this help?
I identified a problem in changing one activity using tab. In one tab activity I'm adding data to my SQLite database, and in the other tab activity I am displaying them using listview(array adapter). But when I come back to add data after adding new items to SQLite, the newly added records are not updated in my listview.
How do I fix this?
You seem to be pulling the list data from a DB. Is there a reason why you are using an ArrayAdapter instead of a CursorAdapter?
Anyway, you should call notifyDataSetChanged() on your list adapter when the data has changed so it can refresh the view.
you can add code to update your listview (via notifyDataSetChanged or some such) by overriding the onResume() method in your activity which is called whenever the activity is brought back to the foreground.
See http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle