[jboss-dev-forums] [EJB3 Development] - Entity hashCode and equals overriding

[fabio valsecchi]

fabio valsecchi [https://community.jboss.org/people/fabiovalse] created the discussion

"Entity hashCode and equals overriding"

To view the discussion, visit: https://community.jboss.org/message/786963#786963

--------------------------------------------------------------
Hi there,

I'm having some problems overring hashCode() and equals() methods of an entity Book. This is my code:

------------------------------------------------------------------------
@Override
public int hashCode() {
int hash = 1;
              hash = hash * 31 + this.isbn.hashCode();
return hash;
          }
 @Override
public boolean equals(Object o) {
if (o==this)
return true;
if (o instanceof Book) {
return (this.isbn == ((Book) o).getIsbn());
             }
             return false;
          }
------------------------------------------------------------------------

The problem is that when I try to add a book to a hashMap like here:

------------------------------------------------------------------------
@Override
public void addArticle(Book book, Integer quantity) {
              Integer *currentQuantity* = cart.getArticles().get(book);

              System.out.println(currentQuantity);

if (currentQuantity == null) {
                  currentQuantity = 0;
        }
        currentQuantity += quantity;
cart.getArticles().put(book, currentQuantity);
    }
------------------------------------------------------------------------

The *currentQuantity* Integer is always null even if in the hashMap there's already the Book that i'm adding.

Maybe it's a problem of my hashCode and equals implementation but i've tried using a hashCode() that return always 1 and with an equals that return always true and *currentQuantity* is still null.
Can someone give me a hint?

Thank you in advance
--------------------------------------------------------------

Reply to this message by going to Community
[https://community.jboss.org/message/786963#786963]

Start a new discussion in EJB3 Development at Community
[https://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2030]

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/jboss-dev-forums/attachments/20130101/11ab9d1f/attachment.html