PagedListAdapter
public abstract class PagedListAdapter<T extends Object, VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter
| java.lang.Object | ||
| ↳ | androidx.recyclerview.widget.RecyclerView.Adapter | |
| ↳ | androidx.paging.PagedListAdapter | |
RecyclerView.Adapter base class for presenting paged data from androidx.paging.PagedLists in a RecyclerView.
This class is a convenience wrapper around AsyncPagedListDiffer that implements common default behavior for item counting, and listening to PagedList update callbacks.
While using a LiveDatasubmitList when new lists are available.
PagedListAdapter listens to PagedList loading callbacks as pages are loaded, and uses DiffUtil on a background thread to compute fine grained updates as new PagedLists are received.
Handles both the internal paging of the list as more data is loaded, and updates in the form of new PagedLists.
A complete usage pattern with Room would look like this:
@Dao
interface UserDao {
@Query("SELECT * FROM user ORDER BY lastName ASC")
public abstract DataSource.Factory<Integer, User> usersByLastName();
}
class MyViewModel extends ViewModel {
public final LiveData<PagedList<User>> usersList;
public MyViewModel(UserDao userDao) {
usersList = new LivePagedListBuilder<>(
userDao.usersByLastName(), /* page size */20).build();
}
}
class MyActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedState) {
super.onCreate(savedState);
MyViewModel viewModel = new ViewModelProvider(this).get(MyViewModel.class);
RecyclerView recyclerView = findViewById(R.id.user_list);
UserAdapter<User> adapter = new UserAdapter();
viewModel.usersList.observe(this, pagedList -> adapter.submitList(pagedList));
recyclerView.setAdapter(adapter);
}
}
class UserAdapter extends PagedListAdapter<User, UserViewHolder> {
public UserAdapter() {
super(DIFF_CALLBACK);
}
@Override
public void onBindViewHolder(UserViewHolder holder, int position) {
User user = getItem(position);
if (user != null) {
holder.bindTo(user);
} else {
// Null defines a placeholder item - PagedListAdapter will automatically invalidate
// this row when the actual object is loaded from the database
holder.clear();
}
}
public static final DiffUtil.ItemCallback<User> DIFF_CALLBACK =
new DiffUtil.ItemCallback<User>() {
@Override
public boolean areItemsTheSame(@NonNull User oldUser, @NonNull User newUser) {
// User properties may have changed if reloaded from the DB, but ID is fixed
return oldUser.getId() == newUser.getId();
}
@Override
public boolean areContentsTheSame(@NonNull User oldUser, @NonNull User newUser) {
// NOTE: if you use equals, your object must properly override Object#equals()
// Incorrectly returning false here will result in too many animations.
return oldUser.equals(newUser);
}
}
}
Advanced users that wish for more control over adapter behavior, or to provide a specific base class should refer to AsyncPagedListDiffer, which provides the mapping from paging events to adapter-friendly callbacks.
| Parameters | |
|---|---|
<T extends Object> |
Type of the PagedLists this Adapter will receive. |
<VH extends RecyclerView.ViewHolder> |
A class that extends ViewHolder that will be used by the adapter. |
Summary
Protected constructors |
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<T extends Object, VH extends RecyclerView.ViewHolder> This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
<T extends Object, VH extends RecyclerView.ViewHolder> This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
Public methods |
|
|---|---|
void |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
PagedList<@NonNull T> |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
int |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
void |
This method is deprecated. Use the two argument variant instead. |
void |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
void |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
void |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
void |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
final @NonNull ConcatAdapter |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
final @NonNull ConcatAdapter |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
final @NonNull ConcatAdapter |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
Protected methods |
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|---|---|
T |
This method is deprecated. PagedListAdapter is deprecated and has been replaced by PagingDataAdapter |
Inherited methods |
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Protected constructors
PagedListAdapter
protected <T extends Object, VH extends RecyclerView.ViewHolder>PagedListAdapter(
@NonNull AsyncDifferConfig<@NonNull T> config
)
PagedListAdapter
protected <T extends Object, VH extends RecyclerView.ViewHolder>PagedListAdapter(
@NonNull DiffUtil.ItemCallback<@NonNull T> diffCallback
)
Creates a PagedListAdapter with default threading and androidx.recyclerview.widget.ListUpdateCallback.
Convenience for PagedListAdapter, which uses default threading behavior.
| Parameters | |
|---|---|
@NonNull DiffUtil.ItemCallback<@NonNull T> diffCallback |
The |
Public methods
public voidaddLoadStateListener(
@NonNull Function2<@NonNull LoadType, @NonNull LoadState, Unit> listener
)
Add a LoadState listener to observe the loading state of the current PagedList.
As new PagedLists are submitted and displayed, the listener will be notified to reflect current LoadType.REFRESH, LoadType.PREPEND, and LoadType.APPEND states.
| Parameters | |
|---|---|
@NonNull Function2<@NonNull LoadType, @NonNull LoadState, Unit> listener |
Listener to receive |
| See also | |
|---|---|
removeLoadStateListener |
public PagedList<@NonNull T>getCurrentList()
Returns the PagedList currently being displayed by the PagedListAdapter.
This is not necessarily the most recent list passed to submitList, because a diff is computed asynchronously between the new list and the current list before updating the currentList value. May be null if no PagedList is being presented.
| Returns |
|---|
PagedList<@ |