用JDBC查询抛出异常

Question

I have following repository method:

@Override
public List<Item> getItemsByName(String name) {
    String sql = "SELECT * FROM ITEMS WHERE NAME = :name";
    Map<String, Object> params = new HashMap<>();
    params.put("name", name);
    return jdbcTemplate.query(sql, params, new ItemMapper());
}

Now I want to throw ItemsNotFoundException when user passed item name that not exists. How should I do it? Should I throw exception when query() method return empty list or is null:

List<Item> items = jdbcTemplate.query(sql, params, new ItemMapper());
if (items == null || items.isEmpty()) {
    throw new ItemsNotFoundException();
}
return items;

Or should I throw this exception when I will get DataAccessException:

try {
    return jdbcTemplate.query(sql, params, new ItemMapper());
} catch (DataAccessException e) {
    throw new ItemNotFoundException();
}

Answer 1

Passing in a name that doesn't exist won't result in a DataAccessException , so that won't work. There's nothing exceptional about an empty result for a query.

However why do you want to throw an exception if the results are empty? Is it an exceptional case for you (ie it's a bug that someone would search for a name that doesn't exist)? If so, it's a valid approach. In the general sense an empty list would probably be better.