MergeCursor, is designed to concatenate two data sets “vertically”, adding more rows.
CursorJoiner is designed to concatenate two data sets “horizontally”, adding more columns. You can think of this as akin to implementing a simple SQL JOIN.
MatrixCursor allows you to build something that implements the Cursor interface out of pure data, that you pour into a two-dimensional data model.
AbstractCursor allows you to wrap your own custom data set in a Cursor interface, overriding the methods that are necessary.
android cursor分类及用法