package auction.model;import java.io.Serializable;import java.util.Date;/** * A single item in a single category, with additional information. * <p> * This is really a very special mapping. The CategorizedItemComponent * class represents a join table. The ER model for this is really * a many-to-many association, but instead of two entities and two * collections, we mapped this as a single collection (in Category) * of composite elements, instances of this class. This simplifies * the lifecycle of the association. Navigation is however only * possible from Category -> CategorizedItemComponent -> Item, not * in the other direction. * * @see Category * @see Item * @author Christian Bauer */public class CategorizedItemComponent implements Serializable, Comparable {    private String username; // This could also be a many-to-one association to User    private Date dateAdded = new Date();    private Item item;    private Category category;	/**	 * No-arg constructor for JavaBean tools	 */    CategorizedItemComponent() {}	/**	 * Full constructor	 */	public CategorizedItemComponent(String username, Category category, Item item) {		this.username = username;		this.category = category;		this.item = item;	}	// ********************** Accessor Methods ********************** //    public String getUsername() { return username; }    public Date getDateAdded() { return dateAdded; }    public Item getItem() { return item; }    public Category getCategory() { return category; }    public void setCategory(Category category) { this.category = category; } // TODO: Hibernate requires this?    // ********************** Common Methods ********************** //    public boolean equals(Object o) {        if (this == o) return true;        if (o == null || getClass() != o.getClass()) return false;        final CategorizedItemComponent that = (CategorizedItemComponent) o;        if (!category.equals(that.category)) return false;        if (!dateAdded.equals(that.dateAdded)) return false;        if (!item.equals(that.item)) return false;        if (!username.equals(that.username)) return false;        return true;    }    public int hashCode() {        int result;        result = username.hashCode();        result = 29 * result + dateAdded.hashCode();        result = 29 * result + item.hashCode();        result = 29 * result + category.hashCode();        return result;    }    public int compareTo(Object o) {		// CategorizedItems are sorted by date		if (o instanceof CategorizedItemComponent)			return getDateAdded().compareTo( ((CategorizedItemComponent)o).getDateAdded() );		return 0;	}	public String toString() {		return  "Added by: '" + getUsername() + "', " +				"On Date: '" + getDateAdded();	}	// ********************** Business Methods ********************** //}