/**
* Swap in a new Cursor, returning the old Cursor. Unlike {@link #changeCursor(AbstractCursor)},
* the returned old Cursor is <em>not</em> closed.
*
* @param newCursor The new cursor to be used.
* @return 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.
*/
public C swapCursor(C newCursor) {
if (newCursor == mCursor) {
return null;
}
C 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);
mDataValid = true;
// notify the observers about the new cursor
onContentChanged();
} else {
mDataValid = false;
// notify the observers about the lack of a data set
onContentChanged();
}
return oldCursor;
}
private void init(Context context, C c, int flags) {
boolean cursorPresent = c != null;
mCursor = c;
mDataValid = cursorPresent;
mContext = context;
if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) {
mChangeObserver = new ChangeObserver();
mDataSetObserver = new MyDataSetObserver();
} else {
mChangeObserver = null;
mDataSetObserver = null;
}
if (cursorPresent) {
if (mChangeObserver != null) c.registerContentObserver(mChangeObserver);
if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver);
}
setHasStableIds(true);
}
