java - Validate null fields in prepared statement -

i have gui takes in fields inserted inside query. when fields empty, it's expected java throws format exception when fields don't match specified type. however, user know input invalid. there way validate when fields inserted in prepared statement empty?

snippet:

string query = "delete racewinners racename = ? "     + "and raceyear = ? , ridername = ? " + "and distance = ? " + "and winning_time = ?";      try {         statement = connection.preparestatement(query);         statement.setstring(1, race_name);         statement.setint(2, race_year);         statement.setstring(3, rider_name);         statement.setint(4, distance);         statement.setobject(5, winning_time);      } catch(sqlexception e) {         system.out.println(e1.getmessage());     } 

to check null, since java 7, have

objects.requirenonnull(somevariable); 

or use overloaded method can specify message. method throw exception if argument passed null.

for other custom logic, you'll have write own validator.

something like

public interface validator<t> {     public void validate(t object, errors errors); }  public class raceinfovalidator implements validator<raceinfo> {     public void validate(raceinfo raceinfo, error errors) {         if (raceinfo.getracename() == null) {             errors.adderror("must provide race name.";         } else if (raceinfo.getracename().isempty()) {             errors.adderror("the race name must not empty.";         }         // etc.     } }  ...  string race_name = ...; ... raceinfo raceinfo = new raceinfo(race_name, ...); raceinfovalidator validator = ...; errors errors = ...; // write implementation validator.validate(raceinfo, errors); if (errors.haserrors()) {     // show user errors } 

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alternatively, put validation in database table schemas, don't recommend it.