Hello,
I'm new in java, and I have a problem. In this class I make a query to the database and return the result but this not return nothing.
When I call the method in the main program, it return an exception that says java.lang.NullPointerException.
This is the code of the class and the main program:
import suite.mod_administracion.entity.*;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.framework.EntityQuery;
import java.util.ArrayList;
import java.util.List;
import java.util.Arrays;
import javax.persistence.EntityManager;
import org.jboss.seam.annotations.In;
@Name("Actividad")
public class Actividad extends EntityQuery {
private static final long serialVersionUID = 1L;
private static final String[] RESTRICTIONS = { };
@Override
public String getEjbql() {
return "select campo from NmcampoPlantilla campo";
}
@Override
public List<String> getRestrictions() {
return Arrays.asList(RESTRICTIONS);
}
@In EntityManager entityManager;
@SuppressWarnings("unchecked")
public List<String> camposActividad(){
return entityManager.createQuery("select actividad from Nmactividad actividad, Nmplantilla plantilla where actividad.idListaPlantilla=plantilla.idListaPlantilla order by actividad.actividad").getResultList();
}
}
This is the main program:
public class probarActividad {
public static void main(String[] args) {
try{
List<String> a = new ArrayList<String>();
Actividad act = new Actividad();
act.camposActividad();
}
catch (Exception e){
System.err.println(e);
System.exit(0);
}
}
}
The method camposActividad() the method should return a List of object.
Can anybody look the code and helpme?
Thanks
