I have a function that returns an id number if the argument exists in the database. If not, it returns null. Is this begging for a null pointer exception? Negative id numbers are not permitted, but I thought it would be clearer to have non-existent arguments returning null instead of an error code like -1. What do you think?
private Integer tidOfTerm(String name) throws SQLException {
String sql = "SELECT tid FROM term_data WHERE name = ?";
PreparedStatement prep = conn.prepareStatement(sql);
prep.setString(1, name);
ResultSet result = prep.getResultSet();
if (result.next()) {
return result.getInt("tid");
}
return null; // TODO: is this begging for a null pointer exception?
}
This is perfectly legal. If you want to avoid a NPE, throw a custom exception. But don't return a negative number. If the caller doesn't check the return value, you will always have a problem. But doing false calculation (because the result is for instance multiplied by -1) is definitely harder to debug than an uncatched exception.