Voyage.java

package net.java.cargotracker.domain.model.voyage;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
import javax.validation.constraints.NotNull;

import net.java.cargotracker.domain.model.location.Location;

import org.apache.commons.lang3.Validate;

@Entity
@NamedQuery(name = "Voyage.findByVoyageNumber",
        query = "Select v from Voyage v where v.voyageNumber = :voyageNumber")
public class Voyage implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue
    private Long id;
    @Embedded
    @NotNull
    private VoyageNumber voyageNumber;
    @Embedded
    @NotNull
    private Schedule schedule;
    // Null object pattern
    public static final Voyage NONE = new Voyage(new VoyageNumber(""),
            Schedule.EMPTY);

    public Voyage() {
        // Nothing to initialize
    }

    public Voyage(VoyageNumber voyageNumber, Schedule schedule) {
        Validate.notNull(voyageNumber, "Voyage number is required");
        Validate.notNull(schedule, "Schedule is required");

        this.voyageNumber = voyageNumber;
        this.schedule = schedule;
    }

    public VoyageNumber getVoyageNumber() {
        return voyageNumber;
    }

    public Schedule getSchedule() {
        return schedule;
    }

    @Override
    public int hashCode() {
        return voyageNumber.hashCode();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null) {
            return false;
        }
        if (!(o instanceof Voyage)) {
            return false;
        }

        Voyage that = (Voyage) o;

        return sameIdentityAs(that);
    }

    public boolean sameIdentityAs(Voyage other) {
        return other != null
                && this.getVoyageNumber().sameValueAs(other.getVoyageNumber());
    }

    @Override
    public String toString() {
        return "Voyage " + voyageNumber;
    }

    /**
     * Builder pattern is used for incremental construction of a Voyage
     * aggregate. This serves as an aggregate factory.
     */
    public static class Builder {

        private List<CarrierMovement> carrierMovements = new ArrayList<>();
        private VoyageNumber voyageNumber;
        private Location departureLocation;

        public Builder(VoyageNumber voyageNumber, Location departureLocation) {
            Validate.notNull(voyageNumber, "Voyage number is required");
            Validate.notNull(departureLocation,
                    "Departure location is required");

            this.voyageNumber = voyageNumber;
            this.departureLocation = departureLocation;
        }

        public Builder addMovement(Location arrivalLocation,
                Date departureTime, Date arrivalTime) {
            carrierMovements.add(new CarrierMovement(departureLocation,
                    arrivalLocation, departureTime, arrivalTime));

            // Next departure location is the same as this arrival location
            this.departureLocation = arrivalLocation;

            return this;
        }

        public Voyage build() {
            return new Voyage(voyageNumber, new Schedule(carrierMovements));
        }
    }
}