/// <summary>Swap in a new Cursor, returning the old Cursor.</summary>
/// <remarks>
/// Swap in a new Cursor, returning the old Cursor. Unlike
/// <see cref="changeCursor(android.database.Cursor)">changeCursor(android.database.Cursor)
/// </see>
/// , the returned old Cursor is <em>not</em>
/// closed.
/// </remarks>
/// <param name="newCursor">The new cursor to be used.</param>
/// <returns>
/// Returns the previously set Cursor, or null if there wasa not one.
/// If the given new Cursor is the same instance is the previously set
/// Cursor, null is also returned.
/// </returns>
public virtual android.database.Cursor swapCursor(android.database.Cursor newCursor
)
{
if (newCursor == mCursor)
{
return(null);
}
android.database.Cursor oldCursor = mCursor;
if (oldCursor != null)
{
if (mChangeObserver != null)
{
oldCursor.unregisterContentObserver(mChangeObserver);
}
if (mDataSetObserver != null)
{
oldCursor.unregisterDataSetObserver(mDataSetObserver);
}
}
mCursor = newCursor;
if (newCursor != null)
{
if (mChangeObserver != null)
{
newCursor.registerContentObserver(mChangeObserver);
}
if (mDataSetObserver != null)
{
newCursor.registerDataSetObserver(mDataSetObserver);
}
mRowIDColumn = newCursor.getColumnIndexOrThrow("_id");
mDataValid = true;
// notify the observers about the new cursor
notifyDataSetChanged();
}
else
{
mRowIDColumn = -1;
mDataValid = false;
// notify the observers about the lack of a data set
notifyDataSetInvalidated();
}
return(oldCursor);
}