Check for non-existence in Java

Question

Tell me whether to use! (exclamation mark) to check for non-existence of results.

if (!rs.next()) { System.out.println("Данные не найдены"); } else { System.out.println("что-то нашли"); }

Nofate ♦ Nofate 32.5k 13 55 86 · Accepted Answer · 2011-07-17T19:22:57

Check out the ResultSet documentation:

Returns: true if the new current row is valid; false if there are no more rows

Conclusion: quite correct.

Nicolas Chabanovsky ♦ 38.2k 54 221 438 · Answer 2 · 2011-07-18T07:45:00

Everything is correct, usually with resultset I use code of the following type:

 while (resultset.next()) { // do something with retrieved data } или if (!resultset.next()) { // в зависимости от логики, вместо ошибки можно выводить сообщение в лог throw new SomeError("No data found"); } // do something with retrieved data

Check for non-existence in Java

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