Android MappingCursorLoader

You can get various cursors which have different position mapping from original cursor with MappingCursorLoader and MappingCursorLoader.Layer.

Let's say your database has data {3, 6, 9, 12, 15, 18},

MappingCursorLoader basically returns the same as CursorLoader.

• MappingCursorLoader with no Layer --> {3, 6, 9, 12, 15, 18}

You can change the position mapping of the original cursor.

• MappingCursorLoader with Reverse Layer --> {18, 15, 12, 9, 6, 3}

You can filter out of the original cursor.

• MappingCursorLoader with Odd-Filter Layer --> {3, 9, 15}

You can use a sequence of layers.

• MappingCursorLoader with Reverse Layer and Odd-Filter Layer --> {15, 9, 3}

You can add group header to the original cursor.

• MappingCursorLoader with Every-10-Separator Layer --> {'010 Group', 3, 6, 9, '1120 Group', 12, 15, 18}

Feature 1 : Layer

• A layer modifies the position mapping in Layer.onMapping(). This is run in worker thread and deliver the result to main thread just like CursorLoader.

• Layers can be added or removed with MappingCursorLoader.setLayers()/clearLayers()/addLayer()/removeLayer(). First added layer is calculated first and the last added layer's mapping is the final result.

• Each layer has its mapping result(=cache) so it can be reused later unless the original cursor or layer order is changed.

Feature 2 : Group

• Like ExpandableListView, you can add groups between cursor rows by MappingCursorLoader.Layer.addGroup(). This should be called in MappingCursorLoader.Layer.onMapping().

• Like ExpandableListView, you can expand and collapse groups by MappingCursorLoader.expandGroup()/collapseGroup()/expandAllGroup(). (I think this is specially useful because ExpandableListView cannot be used with CursorLoader.)

• To see the cursor is group or original cursor data, MappingCursorLoader.getRowType() is provided. It returns MappingCursorLoader.ROW_TYPE_CHILD/ROW_TYPE_GROUP_EXPANDED/ROW_TYPE_GROUP_COLLAPSED. If it is group type, you can get group specific data in the cursor column like cursor.getString(MappingCursorLoader.GROUP_CURSOR_COLUMN_KEY) : group identifier, cursor.getInt(MappingCursorLoader.GROUP_CURSOR_COLUMN_SIZE) : group size

• To use SectionIndexer for groups, MappingCursorLoader.getGroupKeys() and MappingCursorLoader.getGroupHeaderPosition() are also provided.

Examples

I provide some basic layers for example. You can make your own layer or extend these layers. Please run the TestActivity to see what these layers do.

• FilterLayer
• SortLayer
• SeparatorLayer
• ConditionalGroupsLayer

Dependencies

• Android Support Package (android-support-v4.jar) Because of android.support.v4.content.CursorLoader

Release Notes

• v0.1.0 : Initial Release

Source

https://github.com/EaseTheWorld/MappingCursorLoader

Made by EaseTheWorld