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;
}

我很欣赏这种方法的简洁性.但我不是在调用Cursor.close(),我不确定这是不是问题.是否会关闭Cursor并在Cursor.finalize()中释放其资源？否则我将不得不这样做：

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;
}