Package 

Class AsyncListUtil

  • 
public class AsyncListUtil<T>

    A utility class that supports asynchronous content loading.

    It can be used to load Cursor data in chunks without querying the Cursor on the UI Thread while keeping UI and cache synchronous for better user experience.

    It loads the data on a background thread and keeps only a limited number of fixed sized chunks in memory at all times.

    AsyncListUtil queries the currently visible range through ViewCallback, loads the required data items in the background through DataCallback, and notifies a ViewCallback when the data is loaded. It may load some extra items for smoother scrolling.

    Note that this class uses a single thread to load the data, so it suitable to load data from secondary storage such as disk, but not from network.

    This class is designed to work with RecyclerView, but it does not depend on it and can be used with other list views.

    • Method Summary

      Modifier and Type Method Description
      void onRangeChanged() Updates the currently visible item range.
      void refresh() Forces reloading the data.
      T getItem(int position) Returns the data item at the given position or null if it has not been loadedyet.
      int getItemCount() Returns the number of items in the data set.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • AsyncListUtil

        AsyncListUtil(Class<T> klass, int tileSize, AsyncListUtil.DataCallback<T> dataCallback, AsyncListUtil.ViewCallback viewCallback)
        Creates an AsyncListUtil.
        Parameters:
        klass - Class of the data item.
        tileSize - Number of item per chunk loaded at once.
        dataCallback - Data access callback.
        viewCallback - Callback for querying visible item range and update notifications.

    • Method Detail

      • onRangeChanged

         void onRangeChanged()

        Updates the currently visible item range.

        Identifies the data items that have not been loaded yet and initiates loading them in thebackground. Should be called from the view's scroll listener (such as onScrolled).

      • refresh

         void refresh()

        Forces reloading the data.

        Discards all the cached data and reloads all required data items for the currently visiblerange. To be called when the data item count and/or contents has changed.

      • getItem

        @Nullable() T getItem(int position)

        Returns the data item at the given position or null if it has not been loadedyet.

        If this method has been called for a specific position and returned null, then onItemLoaded will be called when it finally loads. Note that ifthis position stays outside of the cached item range (as defined by extendRangeInto method), then the callback will never be called forthis position.

        Parameters:
        position - Item position.

      • getItemCount

         int getItemCount()

        Returns the number of items in the data set.

        This is the number returned by a recent call to refreshData.