Android: do I need to close Cursor objects?

Question

In my database adapter class, I have many methods like this:

public long getContactId(final String phoneNumber) throws SQLException {
    final Cursor cur = mDb.rawQuery(
            "select contact_id from contactphones where number=? limit 1;",
            new String[] { phoneNumber });
    return cur.moveToFirst() ? cur.getLong(0) : -1;
}

I appreciate the brevity of a method like that. But I am not calling Cursor.close(), and I'm not sure if that is a problem or not. Would the Cursor be closed and its resources freed in the Cursor.finalize()? Otherwise I would have to do:

public long getContactId(final String phoneNumber) throws SQLException {
    final Cursor cur = mDb.rawQuery(
            "select contact_id from contactphones where number=? limit 1;",
            new String[] { phoneNumber });
    final boolean retVal = cur.moveToFirst() ? cur.getLong(0) : -1;
    cur.close();
    return retVal;
}

Answer 1

Yes, it's recommended to close the cursor when you are done using that cursor object so that cursor can do whatever house keeping work it wants to do upon closure.

Answer 2

Cursor is not a class but an interface. If your Cursor object is from a SQLite query, it is a SQLiteCursor. In that definition (\Android\android-sdk\source\android\database\sqlite\SQLiteCursor.java), close() is called in the finalize() function. This may be different in other cursor types, since the Cursor interface does not specify this behavior.