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DataSource.Factory

public static interface DataSource.Factory

android.arch.paging.DataSource.Factory<Key, Value>
Known Indirect Subclasses


Factory for DataSources.

Data-loading systems of an application or library can implement this interface to allow LiveData<PagedList>s to be created. For example, Room can provide a DataSource.Factory for a given SQL query:

 @Dao
 interface UserDao {
    @Query("SELECT * FROM user ORDER BY lastName ASC")
    public abstract DataSource.Factory<Integer, User> usersByLastName();
 }
 
In the above sample, Integer is used because it is the Key type of PositionalDataSource. Currently, Room uses the LIMIT/OFFSET SQL keywords to page a large query with a PositionalDataSource.

Summary

Public methods

abstract DataSource<Key, Value> create()

Create a DataSource.

Public methods

create

DataSource<Key, Value> create ()

Create a DataSource.

The DataSource should invalidate itself if the snapshot is no longer valid. If a DataSource becomes invalid, the only way to query more data is to create a new DataSource from the Factory.

LivePagedListBuilder for example will construct a new PagedList and DataSource when the current DataSource is invalidated, and pass the new PagedList through the LiveData<PagedList> to observers.

Returns
DataSource<Key, Value> the new DataSource.

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