Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" because "this.emf" is null
    at org.persistence.RolJpaController.getEntityManager(RolJpaController.java:30)
    at org.persistence.RolJpaController.create(RolJpaController.java:36)
    at org.persistence.PersistenceController.createRol(PersistenceController.java:29)
    at org.logic.LogicController.createRol(LogicController.java:14)
    at org.logic.Main.main(Main.java:16)

package org.persistence;

import jakarta.persistence.EntityManagerFactory;
import jakarta.persistence.Persistence;
import org.logic.Action;
import org.logic.Rol;

public class PersistenceController {

    private static final String PERSISTENCE_UNIT = "IceCreamShopPU";
    private static EntityManagerFactory emf;

    public PersistenceController(){ emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT); }

    ActionJpaController ActionJpa = new ActionJpaController(emf);
    FlavorJpaController FlavorJpa = new FlavorJpaController(emf);
    IceCreamJpaController IceCreamJpa = new IceCreamJpaController(emf);
    InvoiceJpaController InvoiceJpa = new InvoiceJpaController(emf);
    OrdenJpaController OrdenJpa = new OrdenJpaController(emf);
    RolJpaController RolJpa = new RolJpaController(emf);
    SizeJpaController SizeJpa = new SizeJpaController(emf);
    UserJpaController UserJpa = new UserJpaController(emf);

    public void createAction(Action act) { ActionJpa.create(act); }

    public void createRol(Rol rol) { RolJpa.create(rol); }

}